shard target for mongo-perf
fix bug in shard support
accomodate different datetime package behaviors
CAP-1310 - drop collection after each test
make git reporting optional
SERVER-15064: Extend benchRun store and retrieve values
CAP-1215: investigate Remove
fix comments typo
Merge pull request #25 from rzh/shard-cv

Add -shard target for mongo-perf
fix multidb
add Geo query cases
Merge pull request #26 from rzh/cap304-cv

add Geo query cases
add head to explain geo cases design
merge from master