bugfix: swift3k storage driver

GET/HEAD on non-existent vault should receive a 404
PUT block now has content length set as string
Checking of etags is now reliant on the driver itself, and not the API
Merge pull request #106 from TheSriram/swift_bug_fixes

bugfix: swift3k storage driver
fix: swift hook

Import deuce drivers for swift within the hook
Merge pull request #107 from TheSriram/fix_swift

fix: swift hook
Merge remote-tracking branch 'repo/master' into 109_list_vault_2