Update version to 2.7.5

Update version to 2.7.4

Update version to 2.7.3

Update version to 2.7.2

Create version file for 2.7.1

Merge pull request #1 from d0m84/bugfixes

substring is not a valid php function

Pull request #13: Develop

Merge in ZHUB/z-push from develop to release/2.6

* commit 'b84efc59ad09b809427d46aea59b1d33271e12ee':
  ZP-1626 . SafeGetContents is now able to unserialize with opt param. Removed SafeGetContentsUnserialize not more needed. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1626 . Re-added SafeGetContents. Released under the Affero GNU General Public License (AGPL) version 3.

Pull request #13: Develop

Merge in ZHUB/z-push from develop to release/2.6

* commit 'b84efc59ad09b809427d46aea59b1d33271e12ee':
  ZP-1626 . SafeGetContents is now able to unserialize with opt param. Removed SafeGetContentsUnserialize not more needed. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1626 . Re-added SafeGetContents. Released under the Affero GNU General Public License (AGPL) version 3.

Pull request #3: Include fixes for 2.6.3

Merge in ZHUB/z-push from develop to release/2.6

* commit '6ee50d45ca90a6bf2793eb21bc7a54d2d3a0a1cd': (24 commits)
  ZP-1626 . Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1617 ios devices send two responses.
  ZP-1624 . Added MAX_CUSTOM_FILTERTYPE control. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1626 . First version. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1624 . Replaced tabs with spaces. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1617 Meeting response sent twice on an ios device.
  ZP-1625 Save device data in POST requests only.
  ZP-1624 1 year custom sync filter type support. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1623 IpcMemcachedProvider: Increase maxWaitCycles value. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1621 BackendCombined: Fix typo in ImportFolderDeletion(). Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1599 Read instanceid in meetingresponse.
  ZP-1609 Set common start- and end properties.
  ZP-1522 BackendCardDAV: bugfix variable. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1612 BackendCardDAV: return array() in GetGALSearchResults(). Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1612 BackendSearchLDAP: return array() in GetGALSearchResults(). Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1611 CalDAV: Fix invalid content-type. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1522 BackendCardDAV: remove unfinished error handling on Logon(), add option to use '%l' in CARDDAV_PATH, CARDDAV_DEFAULT_PATH, CARDDAV_GAL_PATH and CARDDAV_CONTACTS_FOLDER_NAME. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1522 BackendCardDAV: add usage option for '%l' (local part of username) to CARDDAV_PATH, CARDDAV_DEFAULT_PATH, CARDDAV_GAL_PATH and CARDDAV_CONTACTS_FOLDER_NAME to config file. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1522 BackendCalDAV: add usage explanation for CALDAV_PATH to config file. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-1522 BackendCalDAV: remove remnant code from ZP-1410, add option to use '%l' in CALDAV_PATH. Released under the Affero GNU General Public License (AGPL) version 3.
  ...