Your transaction log is full and you can no longer write to your database. In earlier versions of SQL Server BACKUP LOG WITH NOLOG OR WITH TRUNCATE_ONLY allowed you to carve out the contents of the transaction log without dumping it to disk. For SQL 2012, you will want to issue a command along the lines of the following example – you will lose transactions but you will clear out the log….
BACKUP LOG <databasename> TO DISK = 'NUL:'
In this scenario you can afford to lose transactions and simply want your database back online to do more development work. If you cannot afford to lose data then first thing you may want to consider is backing up the tail. For discussion around tail log backups read here … http://technet.microsoft.com/en-us/library/ms179314.aspx