Subject: Added import and export functionality

Description:
1. Added exportOrganisation method in rpc_main.py
   Purpose:
   Take backup of oraganisation database in /opt/abt/export/*dbname* and
   add organisation tags in /opt/abt/export/bckp.xml file.

2. Added writeToXmlFile method for writting into xml file.
   purpose:
   Pass the xml file path and org details such [org name, from date,
   to date, dbname, rollover flag] as a parameter and write these tags in
   given xml file. These methos is also used in deploy and rollover methods
   for writting into xml file.

3.getAllExportedOrganisations to get all orgs which are exported.

4. Import
   Purpose:
   import database from /export directory to /opt/abt/db
   and write org tags in /opt/abt/abt.xml file

5. Modified two methids in rpc_user.py

6. added command for creating a export dir in /opt/abt.