Bump version to 0.93.0-SNAPSHOT
Fix ClassCastException in NotificationTypeFactory

The "fault_count" attribute of a Notification is always an integer, so
casting it to a double and then rounding it is neither necessary nor does
it work.

Fixes #955
Remove unnecessary casts

Gson used to deserialize numerical values as Double so that ugly casts were necessary
in some places. After the migration to Jackson, these casts can be removed.

Refs #955
Unify x-ticks formatters on old an new graphs
Modify appareance of result histogram graph

To make it more similar to the new sources histogram graph.
Resize all graphs when container dimension change
Unify appareance of field charts with other charts
Use moment-timezone and zone id to get user's date
Use moment-helper to calculate user's local date
Timezone offset should be a number
Remove unnecessary parameter from Graylog2Time

Now we rely on moment-helper to get the right tz offset.
Align dashboard action buttons
Enforce Java 7 compilation target
Add processing of JavaScript to build_release.sh
Fix link in stream processing time notification

That documentation page moved into the general streams documentation.
Improve handling of empty indices in indices view
Remove Gson, fixes #956

Along with replacing the usages of Gson this changeset also replaces direct
usage of Jackson's ObjectMapper with the matching methods from Play's Json
class.
Upgrade to Play 2.3.6
Sync JAX-RS and Jersey with dependencies in REST client
Remove unneeded Ebean ORM dependency