SQl sequence backed RunningNumber
Major cleanup

I got really fed up with the size of the code base in general while
trying to merge #57 and went on a cleaning spree. This change removes
a bunch of excess code and abstractions that were starting to bog us
down.

Highlights:

* string ids are gone, they aren't worth the hassle
* replaced entire sql package with a single class
* factored out a ton of duplicate test harness code in CLITest
* moved LocalBlobTx inside LocalBlobStore for easier field access
* factored more of the managed transaction code out
* separated opening and initializing of BlobStores, fixes #50
* doss.DOSS factory is now gone, decided it was a dumb idea
* made more implementation classes package private
* moved Writable utilities into a Writables class

Merge remote-tracking branch 'origin/persist-generated-ids'

Conflicts:
	src/doss/DOSS.java
	src/doss/local/LocalBlobStore.java
	test/doss/sql/SqlBlobIndexTest.java