replica-safe => replicas-safe
Switch fetch to use a non-deprecated signature of the java driver's .find(). Fixes a bug where congo limits before sorting.
Adds support for :explain on fetch
add background option to add-index!
merge with aboekhoff/congomongo master
adds option to create index in background
adds background to the args list
Merge pull request #121 from dwwoelfel/master

Adds option to create index in background