Fix TableBuilder for non ASCII characters

Fixes http://trac.openmicroscopy.org/ome/ticket/12370

This PR refactors `TableBuilder` and `SQLStyle` to handle non-ASCII characters. To test this PR, 
1- make sure the unit tests are passing (incl. the ones with non-ASCII characters). Any additional tests suggested?
2- from a merge server, create some users with non-ASCII characters in various locations (login, first/last name) and make sure `bin/omero user list` returns a table with columns correctly aligned. Optionally, test the same thing for group names and `bin/omero group list`.