Strip out redundant __new__ to enable object pickling

[vjf]

I'd like to remove the redundant '__ new __' from the wfs classes in order to fix two problems:

1. 'pickle' does not work (you cannot pickle the WFS classes)
2. '__ init __' gets called twice each time the class is initialised. This creates a substantial performance lag on slower network connections.

See #520 for more information.

Thanks.

[geographika]

Reopening to check if this is still the case.

[geographika]

The __new__ overrides date back to at least 15 years - e1d37a1
Since then OWSLib has moved from Python2 to Python3, I'm sure there was a reason at the time, but I can't see a need for the override now. Removing simplifies the code, removes duplicate calls to servers and resolves associated performance issues. Will be merging in the next 7 days - will leave open for comment until then.

Thanks @vjf for the fix.

[coveralls]

coverage: 58.814% (-1.3%) from 60.156%
when pulling 4b9b7cf on vjf:strip_redundant_new
into ae98c20 on geopython:master.

[vjf]

@geographika @landryb Thanks.