Enable repository backup and restore

This capability has integration tests for the following configs:
- modeshape filesystem store
- modeshape infinispan store, filesystem
- modeshape infinispan store, leveldb
Initial implementation of PEP

Resolves https://www.pivotaltracker.com/story/show/55891634

- Prevented Session.save() when RepositoryExceptions are thrown (was in finally block)
- Made all REST API sessions, with or without client login, use ServletCredentials to obtain a ModeShape session
** This is so that we can use the same PEP injection for anonymous clients as we do for logged in users.
- Created a bypass servlet authentication provider, for REST testing w/o auth
- Made all REST calls use servlet credentials
- Added fcrepo-auth-commons to fcrepo4
- Renamed SessionFactory.getSession() methods w/o credentials to getInternalSession(), such that use is clear to devs
- Tied the transaction ID to the servlet session, to prevent duplicate login (now that use consistently use servlet credentials at REST endpoints)
Minor updates to Backup/Restore
Fix FedoraRepositoryBackupTest.java - Get the canonical path of the tmp directory to better mimic what happens in the class being tested.
Non-functional update: Refactor Storage Policy names
Ensure auth-provider singleton is correct in ITs
Add awoods to top-level pom.xml
Update README.md

Added detailed instruction for the format source code save action in Eclipse.
Add Maven artifactId and packaging type to fcrepo-transform