Fixing DTC tests
- Test is now disposable
- Should NOT use buffer pool when reading entire block, block can be of different sizes, and we can't return them while the caller is reading them
Work on RavenDB-1815
Merge branch 'New3' of https://github.com/ayende/ravendb into RavenDB-1815

Conflicts:
	Raven.Tests/Issues/RavenDB_483.cs