rails4 support and also option to get more conditional hashtaggable Value

[mitijain123]

Following are the changes:

• Rails4 support with protected_attributes
• add the optional parameter to the hashtaggables method so that users can pass the conditions they want on the hashtaggings table.
• Older version compatibility, it will work, because I made the argument optional with accept hash.
• Test coverage for the above functionality.

Let me know if you find any issue in the code.