Fix README about bundle_bins

Fixes: https://github.com/capistrano/bundler/issues/47
User proper syntax highlighting for sh and ruby snippets.
- Align command comments properly to README.md.
- Add bundle_jobs default value to README.md.
Indent README snippet properly.
Merge pull request #53 from byroot/patch-1

Fix README about bundle_bins
Merge pull request #51 from tbuehlmann/README-love

Readme love
Add missing parens to bundle_bins example.