Fix bitbucket references

[omit66]

The pypi project link shows: http://bitbucket.org/mchaput/whoosh There are references in the README of this repository as well.

[clach04]

https://github.com/mchaput/whoosh/pull/10

[ThomasWaldmann]

Updating the pypi package metadata should get a higher priority:

• last pypi release was 2016
• pypi metadata points to a non-existent bitbucket repo

That all smells pretty much like a dead project.

OTOH, here on github there is some activity, so guess the metadata should get an update before everybody thinks it's dead:

• update setup.py, README with github URLs
• do a new pypi release (if current master is not releasable, make a 2.7-maint branch and make some sort of safe, stable release from there)
• git tag the release and also do a github release

While doing that, also fix the "Programming Language :: Python :: 2.5" entry in the metadata (if the package shall still officially support 2.x, at least mention 2.7).

[ThomasWaldmann]

@mchaput ^