Revert "Merge pull request #254 from abrody/master"

This reverts commit 3ac7d82951a955b310c87db673ae0992432581b5, reversing
changes made to 5098c81d66ee15d4be60ee9acc81297a80f400ac.
Reduce connect_timeout by elapsed time when retrying.

If a signal interrupts mysql_real_connect, then using the original
connect_timeout would allow the connect method to take longer than
connect_timeout, so reduce by the elapsed time.
Add a default connect_timeout option of 2 minutes.
Readme updates to the Compatibility and Benchmarks section
Merge pull request #505 from dylanahsmith/fix-eintr-retry

Fix connect retry on interrupt and connection timeout
Update specs for Ruby 2.1 Timeout behavior by specifying 'Timeout::Error' as the klass parameter.

With thanks to @bpardee: "if you look at the difference between 2.0 doc and 2.1
doc, it specifically adds the following to the description: The exception thrown
to terminate the given block cannot be rescued inside the block unless klass is
given explicitly."
First pass at separating out connect options from query options
Second pass at separating out connect options from query options