Clarify the purpose and usage of repository

Adds dictionary definition of 'armature' and an overview to README.md.
Minor formatting changes to README
Mix of markdown and html = no go
Finish renaming PEP -> ARM
Merge branch 'master' of github.com:ahpook/armatures
Merge pull request #7 from ahpook/master

Enhance README.md, finish rename in ARM-0