tests: test for dnet_recovery with --dump-file option was added
doc: documentation for recovery dc tests was added
misc: human readable assertion message was added
misc: get rid of *_sync methods usage
misc: elliptics.Session modification was replaced with clone method usage
fix: wrong assertion error message was corrected
misc: EllipticsTestHelper was replaced with elliptics.Session object
fix: missed file was added
misc: assertion was corrected (removed described_as usage)
Merge pull request #24 - tests: test for dnet_recovery with --dump-file option was added