Added feature to inject custom HTTP clients
Merged upstream changes and resolved conflicts. Syntax tweaks per @yguedidi
Merge pull request #84 from SammyK/feature-injectable-http-client

Added feature to inject custom HTTP clients
Stopped canvas helper from throwing when logged out.
Merge pull request #86 from facebook/gFosco.canvas

Stop canvas helper from throwing when logged out.
Removed appToken from test credentials file.
Merge pull request #87 from facebook/gFosco.apptoken

Removed appToken from test credentials file.
Added appsecret_proof handling to FacebookRequest.
Merge pull request #88 from facebook/gFosco.appsecret

Added appsecret_proof handling to FacebookRequest.