Add support for using different databases

[Tattoo]

DbBot should enable users to choose which database is used.

dbbot/reader/database_writer.py and dbbot/reader/robot_results_parser.py are also poorly named, as they are sqlite3-specific. they should be renamed.

It should be possible to give database-specific options from command line too

[leng1987]

Right now dbbot only support sqlite3. I want to know if there is any plan to extend dbbot to support other database such as mysql.
Thanks very much!

[jerry57]

Adding support for PostgreSQL and MySQL would be fantastic. The SQLite3 database is nice for small results and datasets, but adding keywords and having thousands of testcases, the database grows too quickly to be manageable. Please consider adding support for other databases.

[roimvargas]

There is a forked version of dbbot to support MSSQL (https://github.com/NaviNet/MSSQL-DbBot).
But I would like to have support for Oracle DB as well.

Maybe official DbBot do not have to support all these databases but could have a mechanism that other drivers could be configured to replace official sqlite3 support.