Bug 831147: Add cmake to Mac bootstrap script.

The addition of apitrace introduces a new dependency on cmake.  Make sure
this is properly installed in the bootstrap script.  The wiki will need to
be updated separately.
Merge pull request #237 from wanderview/add-cmake-dep

Bug 831147: Add cmake to Mac bootstrap script.
Make get_about_memory.py work even if busybox is installed on the phone.
Merge pull request #238 from jlebar/get-about-memory-busybox

Make get_about_memory.py work even if busybox is installed on the phone. r=dhylands
Some minor improvements to run-gdb.sh

Added pid to the name of the gdbinit file, just to make sure that there weren't any collisions.
If set -x is enabled int he file, it will also print out the contents of the gdbinit file.
Merge pull request #243 from dhylands/dhylands-run-gdb

Some minor improvements to run-gdb.sh
Bug 874065 - Make get_about_memory.py use our fifo, so it should work on an unrooted device.
Merge pull request #249 from jlebar/about-memory-use-fifo-874065

Bug 874065 - Make get_about_memory.py use our fifo, so it should work on unrooted devices.  r=dhylands
Bug 874065 - Update the get_about_memory.py script to pull from /data/local/tmp/memory-reports, to match the Gecko changes in the bug.
Merge pull request #251 from jlebar/about-memory-use-fifo-874065

Bug 874065 - Update the get_about_memory.py script to pull from /data/lo...
Detect number of logical CPUs (threads) on OS X, not "cores".
Let config.sh take common |repo sync| options and pass them through.

For example, -d (check out the manifest revisions, instead of trying to
rebase the current HEADs onto them) is useful when changing branches or
devices, to prevent unwanted rebases that often fail.
Merge pull request #253 from jld/mac-core-count

Detect number of logical CPUs (threads) on OS X, not "cores".
Merge pull request #254 from jld/config-sync-flags

Let config.sh take common |repo sync| options and pass them through.
Update README with two caveats for Mac builds (case-insensitive FS and linker OOM with noopt).
Fixing formatting in README.md.
Removing TODOs accidentally left in README.
Merge pull request #255 from jlebar/readme-updates

Update README with two caveats for Mac builds (case-insensitive FS and l...
Add support to helix.
Add Nexus 4 and JB emulator build support