Add installation, dependencies, usage instructions

Fixes #6.
dropping sections that are outside the scope of this project, partially addresses #17
Merge pull request #23 from gregcaporaso/issue-17

dropping sections that are outside the scope of this project
Update instructions to work with Ipython 2.0
Merge pull request #22 from ElBrogrammer/issue-6

Add installation, dependencies, usage instructions
updated to point to install/usage information on project website