WIP converting realmserver to fluent

Modified DatabaseProvider to accept a connection string, to allow stting
the CharSet and ConvertZeroDateTime required for WCell to function
correctly
Added an event OnDeleteEntity to DatabaseProvider
Created two realmserver database managers, one for Content (i.e UDB) and
one for World (i.e character/instance data
Converted a number of classes to fluent mappings
Refactoring