Test this
Specify exception around imports
Merge branch 'master' into test-platform

Conflicts:
	zimmer/zimmer.py
Write simple transport protocol

Fixes #18
Can write data to specified ports. Data is saved in dictionary
self.last_data.
Reading from 24 must be enabled first.
Echo bit (bit 0) is set when writing to port 20. When reading from 24,
this echo-bit is returned on bit 0.
Merge branch 'test-platform' into operating-hours
Add BDD tests
Add skeleton to read/write to pins
Fill in skeleton with wiringpi API calls