Add "wait_for_start" files

"wait_for_start" will house the 3s wait loop that receives the test
start command from master
'wait3sForTestStartCommand()' sleep functionality

Shall sleep 1s before attempting a second attempt to read from master
Test Case refactor

"wait_for_start" now uses call-back to verify behavior for different
read-from-master scenarios
Correct "wait_for_start_tests.c"

CMock 'Expect' function is overridden by stubbing with call-back,
therefore add responsibility to verify number of read attempts to
'readFromMasterCallback()' and 'tearDown()'

different
read-from-master scenarios
'wait3sForTestStartCommand()' sleep function

Shall sleep 1s before attempting a third attempt to read from master
Refactor 'wait3sForTestStartCommand()'

Further abstraction level in wait loop. Radical improvement to test
suite.
Refactor 'wait3sForTestStartCommand()'

Collect all wait-loop actions (sleep and read) under one function to
simplify test suite for 'wait3sForTestStartCommand()' and improve
readability
Refactor 'awaitTestStartCommand()'

'awaitTestStartCommand()' use 'wait3sForTestStartCommand()' to await the
start command and 'writeStartCommandResultToLog()' to write result to
the log
Add 'writeStartCommandResultToLog()'
Remove "test_control_logging_tests.c"

Remove "read_from_master_callbacks.c"

Remove left-over log entry data from "test_control_tests.c"
'pollMasterForStartCommand()' log invalid command

'pollMasterForStartCommand()' now logs any invalid command