* 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
- Drops some unused indexes
- Applies a computed index to timestamp columns
- Applies a partial index for expired pieces
- Uses BETWEEN to avoid some datetime calls
- Filters expired piece search by those that aren't NULL
* Add in-memory cache for bandwidth and space usage monitoring
* moved some structs around and added error handling for get piece size query
* added to existing bandwidth test. fixed typo
* added test, updates from PR review, added monkit for new methods
* PR review updates. renamed space used methods
* changed bw cache so that only Add updates the cache and it only overwrites when the date moves forward
* moved bandwidth usage to bw and space usage to pieceinfodb
* fixed interface comment
* removed pointer from sync.Once
* 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
* add voucher service on storage node
* config field tag syntax, go routines for requests
* hook up voucher service in storagenode/peer.go
* add voucher config to testplanet
* add voucher config to testplanet
* add voucher response status INVALID, ACCEPTED, REJECTED
* add a test for vouchers service
* handle no row from GetValid, test it
* add trust pool to voucher service
* use trusted list to get satellites
* verify vouchers upon receipt
* test VerifyVoucher
* replace direct reference with an interface in various places
* hide piecePath
* ensure psserver tests don't use path
* ensure psserver tests don't use sql queries directly
