Fix for Android Studio 2.3.x freeze when in Layout Preview. (#215)

Fixes Android Studio 2.3.x freeze when in Layout Preview.
Update plugin versions and build tools to the newest ones.
Library version update to 4.3.1

Merge pull request #212 from stepstone-tech/develop

Merge develop - release of 4.3.0

Merge pull request #200 from stepstone-tech/develop

Release 4.2.0

Merge pull request #197 from stepstone-tech/develop

Merge from develop

Merge pull request #170 from stepstone-tech/develop

Release 4.0.0

Merge pull request #150 from stepstone-tech/develop

Release 3.3.0 from develop

Merge pull request #131 from stepstone-tech/develop

3.2.3 release from develop

* Upgraded version to 3.2.2

* Updated readme as discussed in #107

* Fixed an issue where tab navigation should be disabled when using '…

…tabs' stepper feedback & disabled tab navigation attribute (issue #105).

* Updated Android Support Library to 25.3.1
* Updated library version to 3.2.1

Stepper feedback + sample app main screen redesign (#91)

- Added stepper feedback
- added GIFs for the stepper feedback and tab error animations
- redesigned the home screen of the sample app