Ignore pseudo-system objects in table list

These objects are created by turning on replication and they have column types (sysname, xml) that are not supported by Doctrine. 

According to Microsoft's support, these are "'pseudo-system' object[s]" that appear in the User Table type instead of the System Table type.

https://social.msdn.microsoft.com/Forums/sqlserver/en-US/135ec547-2214-4da3-bd42-5c458759e144/sysobjectscategory
Merge pull request #728 from healsdata/patch-1

Ignore pseudo-system objects in table list