Add support for postgresql:// user scheme
Add support for postgresql:// user scheme

According to the postgresql documentation, this URI scheme is
considered to be the general form.

http://www.postgresql.org/docs/9.2/static/libpq-connect.html#LIBPQ-CONNSTRING

lib/pq,bugreplaydev/pq,erichnascimento/pq,stvp/pq,ScriptRock/pq,jnewmano/pq,dongzerun/pq,VividCortex/pq,beni55/pq,ympons/pq,cbandy/go-pq,amaniak/pq,ympons/pq,henrylee2cn/pq,jnewmano/pq,calebthompson/pq,everalbum/pq,bugreplaydev/pq,springning/pq,sammi/pq,johto/pq,StabbyCutyou/pq