Modifications:
1) Changed signature of methods sqlType and addColumnSql to accept modelField instance
2) Added feature to specify column type in tags using coltype
Added test cases
Added string tag type
Added tag types for oracle
Merge pull request #35 from tejainece/master

Support for custom structs as fields using tags
Add Ravi Teja to contributors
modify tests
update for sqlite3 driver change
update sqlite3.go
update sqlite3.go
Allow existing *sql.DB to be registered to qbs ORM
Merge pull request #41 from yz0075/master

Allow existing *sql.DB to be registered to qbs ORM
fixing bug in Register()

when RegisterWithDB was created, the setting of the driver variable was moved from Register, this caused the opening of the SQL connection to not have a driver string ultimately causing this call to fail. since driver is created outside of the function scope, this passes a compile. 

replaced 'driver' with 'driverName' which fixes the issue
Merge pull request #42 from jchenry/master

fixing bug in Register()