Updating README.md Mac OS X instructions

`brew` should be run as the current user (in most cases, per https://github.com/mxcl/homebrew/issues/9953) and pdftotext is included in the xpdf brew package.
Updating README.md Mac OS X instructions

`pip` is installed by `brew install python --framework`
Added user documentation for local dev environment to roadmap
Merge pull request #1 from marks/master

Just some README.md updates