Fix STORE-143 and STORE-142

The commit fixes compatibility issues in using MYSQL and ORACLE datasources with the StorageManager.

The fix involved:
1. Reading the database type from the datasource
2. Selecting queries based on the type of database
3. Moving all CREATE table logic to the dbscripts folder (storage folder)
4. Adding an extensions folder which allows users to define their own queries for CREATE, SELECT,SELECTALL and INSERT as well as overriding a Table Check
5. MYSQL CREATE scripts has MEDIUMBLOB datatype for storing the file contents
6. H2 and ORACLE CREATE scripts have BLOB datatype for storing the file contents