Rename group to agg_group so that we don't break functions that depend on old behavior

Fix for issue #9
Updates

Added current database to shell prompt
Query's verbose output, index use, and more indicator use one line
Re-enable verbose mode by default
Minor readme update
added gavg function
Updating readme -- no windows or < 2.2 support
fix confusing error message

daemon version is checked, not the version of the shell
Merge pull request #14 from bwaldvogel/patch-1

fix confusing error message
moving examples to wiki
add color to time calculation for non queries
add ability to chain update, upsert, and remove onto find query
add ability to get environment variables from mongo shell

useful for getting things like a user's home directory:
var home = getEnv("HOME")
add select as an optional way to project
add ability to use one() as terminal that retrieves one document
update README.md
prompt now shows rs status
add rs status to readme
2013!
remove auto-multi (available through update chainable)
adding filter as alternative to overloaded find
add replace method which updates a single document