adds lowercase to TZ pattern

[Rock-HOG]

some log entries may show lowercase timezone.

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[Rock-HOG]

I have signed the CLA.

Thanks

[jsvd]

would you mind adding tests for this change? there are many examples of tests in the spec/ folder

[kares]

Thanks for the PR, seems like this has been stale for a while.
Since the PR was opened a discussion went on at #172.

Lower-case names seem quite uncommon and instead the issue focuses on matching more time-zones.
I know Ruby would match such strings but that is more of an implementation detail I believe than an actual intent.
Going to close this one in favour of #235, if anyone is seeing lower-case TZ identifiers produced please let us know more details (sample logs) on what kind of apps/services produce them.