Fix README links.

cbugg: close bug-296
Don't allow group=0

cbugg: close bug-323
add flag for access log
add support for ptr=_id to return document id

This is useful when combined with the identity reducer to return
the list of all document id's that were a part of this group.

For example:

    /database/_query?ptr=/metric/samplea&reducer=avg&ptr=_id&reducer=identity&group=1000000000

This query returns the average value of /metric/samplea and the list of all
document ids in this group.
Don't accept non-json writes.

cbugg: close bug-432
Tool for batch compacting.

cbugg: close bug-481
Remove JSON benchmark.

We no longer parse this way, and jsonpointer has its own
benchmarking.
fix so tests can run

previous commit removed last reference to this import
see b8cb1f9aae074f293187758cf5893aed30e23d12
change from *string to interface{} for matched values
update TestPointers test case to work with interface{}
added 2 new reducers that work with objects

obj_keys returns all the keys of the matched objects in the group
obj_distinct_keys returns all the distinct keys of the matched objects in the group
fixing TestNilReducers that I broke accidentally
added reducer distinct

distinct works like identity, but removes duplicate values
if returned value is array or object it is omitted
if returned value is numeric it becomes a string
Configurable number of concurrent compaction workers.
Benchmark the stdlib RFC3339 to compare against mine
Cache fix from upstream API change.
Cleaned up query processing.
Minor aesthetic changes.
Don't need to close request bodies.
Don't log fast queries