Add Codebase Security Plan and Structure Changes

Hi Tony,

We've made changes in the code and structure as you asked.

1. Move code to api directory.
2. Make security changes in the code as describe on wiki http://open-emr.org/wiki/index.php/Codebase_Security#Plan and remove duplication binding.
3. Create api_tokens table to hold tokens instead of tokens table. Remove medmasterusers table and incorporate extra fields of medmasterusers table in users table (fields that are not available in users table).
4. Add "Allow use of REST API server?" settings in Administration->Globals->Connectors and place check in the code to check the settings. API only works if user enable settings. Add settings in library->global.inc file and you can find file in 
openemr->library directory.
5. Add copyrights text in all api files as describe on wiki http://open-emr.org/wiki/index.php/How_to_Document_Your_Code_Properly#Page-Level_DocBlock

Please review the code and let us know, if any changes are required.

Thanks,