bulk: Handle upsert on MongoDB < 2.6 with non-objectid _id fields.

Server versions before 2.6 only return the 'upserted' field in an update
result when the upserted _id is an ObjectId. If the user provides any
other value for _id in the query spec, or update document (for a replace
operation) the upserted field is not returned. This causes invalid counts
for nUpserted in the Bulk API result set.

This fixes CDRIVER-372.
Release 0.96.2
build: post-release bump.
build: bump libbson
build: rpm build improvements.
build: bump libbson for alignment fixes.
build: bump libbson for gettimeofday change.
build: fix warning.
build: bump libbson for sparc fix.
ssl: load a SSL_CTX on startup to ensure ciphers are available.
build: start on autobuild.sh script.
build: disable static, disable silent rules in autobuild.
build: incremental work on new build automation.
build: clean before 64-bit build.
build: work on autobuild script.
build: make solaris10 package build using autobuild.sh
build: redirect which stderr to /dev/null
build: rename autobuild.sh to mci.sh and drop legacy packging script.
build: fix mci.sh on sparc solaris 10.
build: start on building RPMs in an automated fashion.