Upgrade to Lucene 4.2.1
Call onFailure for every exception case even in the case of an error / runtime exception

Closes #2848
Added `clean` to mvn command. In some cases when recompiling not all changes are detected (E.g. file move, already compiled classes don't get this change).
Fixed issue where a doc is omitted from the hits if it has no geo point and sorting is based on geo distance.
Closes #2851
Improve stability of MinimumMasterNodesTests
Improve stability of ClusterHealthTests
Beef up FieldData tests by running one on one duells
Allowing to disable timestamp field mapper after enabling
Allowing to disable index field mapper after enabling
Allowing to disable size field mapper after enabling
Merge branch 'field-mappers-fix' into master

This fixes #2136 and allows to disable the timestamp, index and size field mappers on runtime.
Fix for ttl fieldmapper to support disabling correctly. Also returning only booleans, not enums in toXContent
Returning configuration of root field mappers toXContent method only if they are enabled
Cleanup ScriptDocValues. This commit adds a getValues method to all ScriptDocValues for easy access
in scripts via doc['field'].values / value.
Settings / Config: Allow to explicitly specify external environment variable syntax, in which case its optional
fixes #2855
Catch Throwable when listener is called rather then Exception to prevent possible hangs if fatal exceptions or errors are thrown
Thread Pool: Update default settings (move from default cached to fixed)
closes #2858
allow to disable the optimization of removal of ords on single value numerics/geo field data
field data settings in the mappings can have ordinals=always option
Added test that compares concurrent facet execution results with a serial execution result
beef up term facet tests