Multiple tangodb without dynamic auth
Support Tango multi db URIs. Fixes #929 (closed)
This MR is similar to !1270 (merged) but this one doesn't use the reserved word ".dynamic_auth.". It just lets PyTango to get the correct db and uses it as usual. Note: only 1 MR must be merged, either this one or !1270 (merged). We need to choose which one we want to include.