docs: fix wording for insert example
doc: add section on update for getting-started.
tests: up load test command count for longer running tests.
socket: update ingress bytes counter.
doc: manually -lbson-1.0 for gcc.
doc: add counters documentation.
counters: always use atomics for counter increments.

This allows our counters to have full correctness. It is a bit slower
in the contended and non-contended case, but when using per-cpu counters
it is still significantly faster than atomics on a single cache-line.

See https://raw.githubusercontent.com/chergert/counters/master/samples/core-i7-3667u/mutations.png
for performance characteristics.
doc: add troubleshooting page
doc: fix typo
doc: add example for running a command.
doc: add basic authentication docs.
doc: add OpenBSD 5.4 to list of supported operating systems.
doc: add x509 docs.
doc: add authentication docs.
doc: add kerberos documentation.
doc: use <cmd> and <var>
fix a missing static on a once_init
correct aggregate cursor functionality

handle limit appropriately for aggregates.  A few things were broken.

Needs a fix in libbson as well
Merge pull request #33 from hanumantmk/CDRIVER-359

correct aggregate cursor functionality
tests: deprecated mongoc_collection_bulk_insert() returns different values on 2.4 and 2.6