Implemented constructors
Started testing content type handler
Added: A bunch of content type handler tests

Only stubs. Willr equire further work
Added description to content type group and simplified naming
Updated type group table

Now reflect the struct used in SPI more accurately
Introduced changed columns in every table

Those columns contain the date of the last change to the column. Really
useful for debugging and a common MySQL pattern.
Implemented: User CRUD
Adapted role schema to SPI
Tested & Implemented most of user handler
Implemented: Creation and storage of content type groups