Add generation statistics report

[ladisgin]

After tests are generated, we want to get a generation statistics report.
It can be represented as csv file where each row contains statistics for one file which tests were generated for.
Statistics should include the following information:

• Total KLEE time (from klee-stats)
• Solver time (from klee-stats)
• Time spent in object resolution (from klee-stats)
• Maximum memory usage (from klee-stats)
• Number of tests generated in different suites (regression / error)
• Number of functions which tests were generated for