support turning on and off usb stick recording
add documentation
Merge pull request #53 from sameerparekh/dev-unstable

Turn on and off USB stick recording
Motor PWM added to Navdata. README updated.
Minor readme edits
Upgrading to Parrot SDK 2.0.1
Patches to make SDK 2.0.1 compile and link with ROS driver
Bug fixes in macros
README updated for SDK 2.0.1
Minor fix - fixes #68
Remove `target_versions` prior to building the SDK
Minor edits in README file.