Adding BGCoder tasks section

Added tasks from:
2011-2012_C#_IntermediateExam1
SampleExam - all
TestExam - all
TODO.txt - todo list
2012-2013_C#_IntermediateExam1
Exam1_27Dec2012 - all
Exam1_29Dec2012 - tasks 1, 2, 3, 5
TODO.txt - todo list