pushb: fix formatting of help message
pushb: improve config file handling
pushb: add 'link' and 'devices' commands
pushb: support reading stdin for note body
Merge pull request #1 from dgryski/pushb-fixes

Pushb fixes
NewWithClient: allow injecting other http.Clients
set Authorization header by hand

The Go AppEngine SDK doesn't allow URLs with a "username@" prefix and
requires that the Authorization header is added manually.
Merge pull request #2 from dgryski/http_client

Http client fixes