HITL: Initial import of testing scripts
HITL: Device preparation script working
HITL: Script to print device info before starting a test
HITL: prepare_test.sh checks files exist
HITL: prepare_test.sh should build hub_ctrl
HITL: Refactor device power script to just power cycle

This works around the problem that the device file disappears when the port is powered off.
Modified serial_link.py to record SBP logging data.

serial_link.py can now log serialized, timestamped SBP messages to a
consistently-named logfile, but only if libsbp is available for
serialization.

r=@fnoble,@cbeighley

Closes #186.
Cleanup serializaton logger.

Moves log formatting (timestamps) into actual callback.
Saving ephemerises
More efficient saving of ephemerises
Missing slash
Merge pull request #194 from imh/master

Added ability to write out ephemerises
HITL: If we are using the 'null' toolkit then mock the SVGButton class

Bit of a hack, submitted an issue to enable to get SVGButton working with the null toolkit

https://github.com/enthought/enable/issues/162
HITL: Use null toolkit for print_device_details.py

Otherwise imports from settings_view.py will complain that there is no X windows

Also, some cleanup
HITL: Reduce delay in prep script (for great reliability!)
Bit of refactoring for SBP logging.

0. Added fallback SBP definition since libsbp isn't out yet and its
use here is completely superfluous.
1. Reverted msg_type callback interface.
HITL: Update prepare_test.sh to program devices one at a time

Works around swift-nav/piksi_bootloader#5
Merge pull request #193 from mookerji/183-spectesting

Modified serial_link.py to record SBP logging data.
HITL: Add delay at end of prepare_test.sh to wait for Piksis to boot up
serial_link: get_message return type not updated for new format in one place