Do not warn for out-dated sqlite for all versions < 3.3.13

[Former user]

In #302 a warning was added to /databases/sqlite.py if the sqlite3 library version is below 3.3.13. The reporter of #302 reported several test failures with sqlite older than 2.1.3. But r2528 added warnings for sqlite3, too.

Using sqlite 3.3.6 (CentOS 5) with SQLAlchemy 0.3.10, can run the test suite without problems: The only output besides dots is

/SQLAlchemy-0.3.10/lib/sqlalchemy/util.py:147: RuntimeWarning: exceptions.Exception('this exception should be stated as a warning') ignored
  warnings.warn(RuntimeWarning("%s('%s') ignored" % sys.exc_info()[0:2](0:2)))

Therefore I think there should be no warning at least for sqlite 3.3.6.

Please send a notice to felix dot schwarz at web dot de if you add a comment here.

[Mike Bayer]

the only warning in current tip is against 2.1.3. there's some other features that transparently adjust themselves based on versions 3.2.3 and 3.3.8. I've adjusted the code to be a little more consistent in 4291e0b316438a81121de1170fe902dc375a4969