updated readme

fixed hmi, added VariableState fake model, fixed export

0.7.0.b4
- fixed reinit loop in daq daemon
- added restart of daq when Scaling model has changed
- fixed hmi.widget save without a title
- fixed export.handler (wrong start and enddate)
- fixed export to file, check of arrayindex
- added backend table (VariableState) for current values in the
database
- fixed crash of hmi admin when widget has no title
- added unixtime value in web hmi (experimental)
- fixed custom html panel variable not uptading in hmi
- added restart_daemon field in background task model

updated daq and hmi, removed unused code

- removed separate handler files for daq
- removed seperate HMIVariable model
- added restart of daq when Variable or Device model are changed
- added support for different byte order of aquired data
- fixed support for U/INT64 and U/INT32 datatypes
- removed chart_set from hmi
- updated docs
- removed unused code

updated changelog

updated documentation

added migrations