DOC: Add note on getting help using StackOverflow

Added a note to the README file for people to request help using
StackOverflow using the `biom` tag.
REL: updated version string format, fixes #554
DOC: noted change
Merge pull request #555 from gregcaporaso/issue-554

updated style of version strings
Merge pull request #549 from ElDeveloper/stack-overflows

Thanks @ElDeveloper!