Merge pull request #3 from MNUthai/master

Implemented thread_sleep, and passed 2 tests: alarm-single and alarm-multiple
Merge pull request #4 from MNUthai/master

Alarm Test is working. Priority is not.
Merge pull request #5 from MNUthai/master

Implemented thread_set_priority and insert by sorted into sleep_list
Merge pull request #6 from MNUthai/master

updated thread_set_priority()
updating synch and thread
Merge remote branch 'upstream/master'