Replaced literal string 'dualIdle' with constant State.DUAL_IDLE
Replacing direct references to .browser with the getter method browser()
Added tests to cover behavior related to State.UNPAIRED
Added test of the Trader getter and setters
Changed direct references to the Trader object into calls to its getter method
Changed direct references to the Trader object into calls to its getter method
BillValidator, changed a few direct references to the object into calls to Brain.getBillValidator() instead.
Changed direct references to the Pairing object into calls to its getter method
Changed direct references to the Pairing object into calls to its getter method
minor. corrected formatting on test names
Added tests for the remaining elements of STATIC_STATES in the 'exitOnIdle' unit test
Replaced literal string 'unpaired' with constant State.UNPAIRED
Minor. moved the _unpair() function up near the _unpaired() function for readability's sake.
Added tests for _unpair
Added ACCEPTING_BILL and BILL_INSERTED
Merge pull request #43 from haxwell/canary-replaceLiteralStringsWithConstantStrings

Canary replace literal strings with constant strings
Changed Brain.getBillValidator() to Brain.billValidator(), and added Brain.setBillValidator()
Added _billInserted unit test
Merge branch 'canary' into canary-replaceLiteralStringsWithConstantStrings