Try to speed up build by optimizing travis/graylog2-server.sh
Upgrade to sbt 0.13.5
Consolidate sbt build

We got rid of the 'package-snapshot' command and can now use 'universal:package-zip-tarball'
directly. The name of the artifact is overridden in case of a SNAPSHOT build and the example
config will be mapped into the archive.

Selfie of the author of this changeset during basically every stage of development and
contact with SBT:

http://31.media.tumblr.com/bcaca0957cae39e4fd6fa056167f3603/tumblr_n8eup6Xzjv1s373hwo1_400.gif
Merge pull request #888 from Graylog2/fix-snapshot-directory-in-tgz

Fix directory in snapshot archives
Speed up Travis CI build by removing unused services
Possible fix for issue #890

- added additional check to ensure sampling of data only applies to search result chart widgets
Adding correct source field for radios when showing messages from input.

Fixes #856
Bumping version to 0.21.0-beta3.
Bumping version to 0.21.0-beta4-SNAPSHOT
Only append width query parameter if it has a value, refs Graylog2/graylog2-server#696
Generating getters/setters for now as play is unable to do it.
Bumping version to 0.21.0-beta4.
Bumping to next snapshot.
Merge branch 'master' into issue738
JavaScript UpdateManager now checks for user preferences to determine if updates should occur without window having focus