Port procrustes module

Ports the procrustes module, along with the tests and improved
documentation that's compliant with @jrrideout's annoying guidelines.
Merge branch 'master' of git://github.com/biocore/bipy into port-procrustes
Fix imports and move to skbio
Move procrustes to maths.stats.spatial
Finally, nuke all occurrences of bipy
Address comments by @wasade
Add brobsessive suggestions by @ElBrogrammer
Merge branch 'master' of git://github.com/biocore/bipy into port-procrustes

Conflicts:
	doc/source/index.rst
Merge pull request #151 from ElDeveloper/port-procrustes

Port procrustes module