Upgrade to version 1.2.0

1. General: set internal platform time zone to UTC. All timestamps are
saved and returned in UTC reference.
2. API: Modify input timestamp format to dd/MM/yyyy'T'HH:mm:ssZ: Z is
optional and its default value is UTC.
3. API catalog: new sensor attribute 'timeZone'. Useful to register which.
timeZone is used by sensor observations when it is different to UTC .
4. API: make API error messages more user-friendly and new attribute
errorDetails.
5. App Catalog: new property 'catalog.default.timezone': default value is
UTC and it is used to format timestamps before show it in graphics.
6. Tests: custom logback config to unit tests.
7. Fix some minor bugs.