[REFACTOR] code cleanup in SharedProjectDecorator

Moved declaration of all variables to the top of the class and declared
them final when possible. Also changed final static variable naming to
match the Java coding conventions.

Change-Id: Ic275230fc0c4e2cdc4b54d574e9944fe3f1d0a1a
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1115
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>