updated release notes for 2014_12 (1st cut)
Fixing overlap parameter issue (DM-1678)

Add required configuration option part.default-overlap which will be
stored as per-database overlap value in CSS. Per-table value is still
stored as before (from part.overlap config parameter).
Merge branch 'u/salnikov/DM-1678'
DM-1658: Document 'git bisect' use
Rename data loading script
DM-1658: Ignore in git symlinks to startup scripts
Sort ups table file
Add partition dependency required by data loader
Add data loader option to keep input data
Move emptyChunk from etc/ to var/
Improve emptyChunk management

QSERV_RUN_DIR/var/lib/qserv will contains
emptyChunks file for each loaded database.
Loader will create this directory if it
doesn't exists.
Clean code and comments