Add config and simplify the code.

* Add config parser
* simplify the code(function not changed)
* simplify log setting, remove the date and time part
Add absolute position plotting
Bug fixed by forking process for each timeit!

* Separate the environment for each timeit, this may use more
  system ressource but it has fixed the bug that the program
  can not distinguish compiled modules of different commits!

* This method also helped to prevent the memory from incressing
  after each timeit. (Because the timeit module seems not managing
  collecting data after being called. For example, nqueens can
  exhaust as many memory as we have if the number and repeat
   are not low)
Delete useless curves on plotting

* worst, mean, median...
Fix bug of the default commits.

* If no commit selected, the script choose all the commits of the given branch
* If no branch selected, the script choose the master.
Create README.md
Add benchmarks

* nqueens
* int_sum
* float_sum