* storagenode: remove datetime calls in favor of UTC
datetime only has second level granularity whereas string
comparisons don't. Since we're wiping everything anyway, it's
easier to just use UTC everywhere rather than migrate to
datetime calls.
* add utcdb to check that arguments are utc
* storagenodedb: add trivial tests to ensure calls work
This at least tests that all of the timestamps passed in are
in the UTC timezone.
* fix truncated comment and change migrations to be UTC
* remove infodb locks and give a unique name for each in memory created.
* changed max idle and open to 1 for memory DBs. fixes table locking errors
* fixed race condition
* added file based infodb test
* added busy timeout parameter to the file based infodb for testing
* fixed imports
* removed db.locked() after merge from master
