OTC-347: Add token management (similar to Policies app) in Claims app

[malinowskikam]

Changes:

• Added API_VERSION build config field, which is used to select API version used with the app
• Added reading/writing code to Global.java
• Added token related functions to Global.java
• Moved rar password related code from Settings to Global (to be reused across the app)
• Added token validation and expiry date
• Changed library used to perform HTTP requests from cz.msebera.android.httpclient to org.apache.http (the same as in policies app)
• Refactored ToRestApi.java to have only one method to perform GET and one for POST, overloaded for compability
• Splitted Synchronize.java into SynchronizeActivity, containing UI and interactivity and SynchronizeService, containing claim sync logic

Additional changes:

• Upgraded gradle version
• Upgraded Java language level to 8
• Cleared app import list
• Added proguard-rules.pro file, declared in build.gradle, but not present
• Changed CaptureActivity to be targeted by class and not by intent-filter (Fixing bug where every Imis android app would show when CaptureActivity is invoked)
• Added ImisActivity abstract class, containig some android UI related functionality (login, dialogs, broadcasting) which was previously copied into every activity separately
• Deleted a lot of copied functionality from classes that where changed in the OTC-347
• Changed some interface implementations to lambda expressions in modified classes
• Deleted commented code from modified classes

https://openimis.atlassian.net/browse/OTC-347