README: reindent
add initial code from @adamjspooner

https://github.com/adamjspooner/meteor/commit/53ae2d73b7e9b350d6c7024e9af8cef4c2141841

https://github.com/meteor/meteor/pull/1065
reorder and add missing commands

Use the same order as `meteor help` to ease maintenance later.

Tested with Meteor 0.8.3.
indent commands list
add args and file-based cache
use simpler/faster in-memory cache
complete example, add install instructions