Add ability to specify README.md directory, path; fix Guide paths; fix Pages sidebar titles

for non node.js projects it'd be cool to specify README.md only for javascript assets (as they may be in app/assets/javascript, for example), not for whole project
Fix RegExp for names replacements
add --readme option
Merge pull request #4 from kerbyfc/patch-2

Add ability to specify README.md directory, path; fix Guide paths; fix Pages sidebar titles