HSEARCH-1460 Renaming old performance module into sandbox
HSEARCH-1460 Adding new Hibernate Search performance test harness
HSEARCH-1460 Aligning capitalisation of module names
HSEARCH-1460 Updating profiles. Removing hsearch440 and hsearch430 and adding hsearch450
HSEARCH-1487 Upgrade to Hibernate ORM 4.3.1.Final
HSEARCH-1485 Update H2 testing database to avoid some issues under load
HSEARCH-1260 Refactor existing MassIndexer components

- Pipeline components in the MassIndexer don't need a new instance per thread
- Avoid starting threads in the constructor
- Use the new ErrorHandledRunnable to cleanup ugly usage of ErrorHandler
- Refactor Runnable implementation of MassIndexer to share a common parent
HSEARCH-1260 Merge the two DocumentBuilder indexing phases in a single one
HSEARCH-1260 Simplify HibernateSessionLoadingInitializer as we don't have to deal with detached collections anymore
HSEARCH-1486 Minimize allocation cost of iterating on metadata fields
HSEARCH-1260 Documentation updates regarding the removed stage and update configuration suggestions
HSEARCH-1488 Centralizing release plugin config. Skipping tests during release and using a local git checkout
HSEARCH-1488 Changing performance module profiles to work with release plugin

Also renaming artifact id of sandbox module to avoid duplicate artifact ids
HSEARCH-1488 Adding optional backends to the pom to include them into dist bundle and avoid buld warnings