Oracle: allow running the tests using Kerberos authentication

[Gabor Gombas]

Hi,

test_oracle.py assumed the username can be extracted from the connection URL, but that's not true if Kerberos authentication is used (like ./sqla-nose.py --dburi=oracle://:@TNSNAME). Ask the name of the connected user from the database instead.

Gabor

[Mike Bayer]

• Fixed bug in oracle dialect test suite where in one test, 'username' was assumed to be in the database URL, even though this might not be the case. Fixes #3128

→ <<cset 0eb53b2e7936>>

[Mike Bayer]

• Fixed bug in oracle dialect test suite where in one test, 'username' was assumed to be in the database URL, even though this might not be the case. Fixes #3128

→ <<cset 577c719a1158>>