Dropping GStreamer 0.1 Support

[Michael McConville]

Hi, everyone.

GStreamer 0.1 hasn't been maintained for a few years and the community
is trying to get everyone onto 1.0. However, Pidgin 3.0 currently
supports both versions.

Dropping 0.1 would improve voice/video support, but would break
voice/video for some long-term support operating system releases. Are
there any objections to doing so?

There are more details at the bottom of my wiki page:

    https://developer.pidgin.im/wiki/mmcco