first stab at supporting database 'url' for connection

tests to come
fix CS
fix wrong variable use in parse_url
fix return values
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
fix undefined $url
some tests for database URLs
fallthrough scheme tests, and turns out underscores are a no go :(
support dashes in schemes for db drivers, translated to underscores
remove underscore from method name as per feedback
remove underscore from member name as per feedback
erp, typo, wat
early assign as per feedback
fix backslash prefix
remove redundant check as per feedback
Update index name quoting in MySQL table creation
Move index name quote to abstract
Only quote in get*SQL() methods
Merge pull request #728 from healsdata/patch-1

Ignore pseudo-system objects in table list
Use name rather than index object