sorted/postgres: test with docker

Also, NewKeyValue now automatically creates the required tables.

http://camlistore.org/issue/263

Change-Id: I02dd7660ee08c2eaeec17131622d6f581fdd6c55
camput init: ring/key related fixes

1) Removed exec call to gpg, because it automatically looks in .gnupg/,
which we don't use anymore as a default.
2) Now taking into account global --secret-keyring flag.
This flag is now in osutil.
3) New or modified funcs in osutil
4) Made sure --gpgkey works too.
5) Cleaned up error messages and hints.

Context: http://camlistore.org/issue/364
         http://camlistore.org/issue/368

Change-Id: I2e51032ed0597da656db100d72f5588b37308e1a
blobserver: more docs on MyPrefix

Change-Id: Icf7fa540c7eb7400719e6baf74f3be746615a4f5
Merge "blobserver: more docs on MyPrefix"
Merge "camput init: ring/key related fixes"
context: add Context.SetHTTPClient

Change-Id: I10729215cacb5d6faf2ffaedc12c9d7449a1d6a3
types: add EmptyBody

Change-Id: Ic0cc6cae6debb20fbc15bd95692e8565171eae49