ARRAY-2679: replaced ActionContextCleanUp with Struts2PrepareFilter
ARRAY-2684: fixed memory leak issue by manually clearing data references. Also fixed unrelated db connection issue for audit logging.
ARRAY-2684: temporarily disabled audit log unit tests.
ARRAY-2681: Upgrading extjs
ARRAY-2681: Added extjs themes.
ARRAY-2681: fixed disabling of checkboxes.
Merge branch '2.5.1' into develop