Renamed kAFOAuthCredentialServiceName to kAFOAuth1CredentialServiceName

Fixes a duplicate symbol error when linking to AFOAuth2Client.
Fixes #79. Don't ignore parameters on GET requests.
Merge pull request #83 from madninja/bug/oauth-signing

Fixes #79. Don't ignore parameters on GET requests.
Merge pull request #81 from ejensen/patch-1

Rename kAFOAuthCredentialServiceName to kAFOAuth1CredentialServiceName
Bumping version to 0.3.1
Merge branch 'master' of github.com:AFNetworking/AFOAuth1Client