Merge branch 'issue-8-remove-database-configuration' into 'master'

Issue 8 remove database configuration

This merge request sediments what we have discussed along the week.
Basically I removed bob.bio.db package and move the BioDatabase and BioFile classes to bob.bio.base.
I will branch the bob.nightlies to better do the integration tests.

I will leave this merge request open, just to not forget

See merge request !37