Deprecation warnings

[misja]

Both cgi.parse_qs and inspect.getargspec will be deprecated. This pull will replace these with urllib.parse.parse_qs and inspect.signature respectively if available.

[mreiferson]

@misja looks good to me, thanks!

[misja]

@mreiferson if you intend to create a release including this change, please hold since I just noticed two issues with replacing inspect.getargspec by inspect.signature -

• the change tries to load inspect.getargspec first which will still trigger the deprecated warning
• I naively assumed the return type of inspect.signature would be equal to inspect.getargspec but it is not and will break things (tests, tests, ...)

I'll add a proper pull second half next week to have this sorted.

[mreiferson]

Thanks for validating and giving us the heads up, I'll wait for your PR!