Groups filters don't work

[Rodion Kulakov]

groups/get method don't work if $filters is not omitted because all keys in array are the same $filters = array( 'group' => 'account_name/group_slug', 'group' => 'other_account/group_slug' );

[Alexandru Guzinschi]

fix and close #12

• Filters from group/get accepted an array with duplicate keys.
• Parameters sent with GET request must not be encoded (changed again ?) -> Wrapped http_build_query in urldecode

→ <<cset a5182bd46516>>