Allows to set the account meta key by setting hp_account_meta_key, needed to generate temp urls using the HP provider, explicitly, instead of using hp_secret_key. If hp_account_meta_key is not given hp_secret_key is used as hp_account_meta_key.
HP uses a different strategy to create the signature that is passed to swift than OpenStack.  As the HP provider is broadly used by OpenStack users the OpenStack strategy is applied when the @hp_account_meta_key is given.
Adds Fog::Storage::HP::File#url method to enable compatibility with Fog::Storage::AWS::File
Fixed bug undefined local variable or method account_meta_key
Bugfix: @hp_secret_key instead of @hp_account_meta_key required in storage.rb:186
Avoids Digest::HMAC.hexdigest to remain 1.8.7 compatibility
Remove File#url
Renames hp_account_meta_key to os_account_meta_temp_url_key
Merge pull request #1912 from anynines/master

OpenStack Temp URL Support and AWS::File compatibility