refactor Sps generation
parse only add and UT
Merge pull request #1542 from sijchen/review

[Encoder] refactor Sps generation: passed review at https://rbcommons.com/s/OpenH264/r/930/
Merge pull request #1547 from huili2/ParseDecode

parse only add and UT: passed reviewed at https://rbcommons.com/s/OpenH264/r/910/
    add one more conditin for statistics printing to avoid timestamp problem
Merge pull request #1548 from sijchen/after_review

[Encoder] add one more condition for statistics printing to avoid potential timestamp problem
Merge remote-tracking branch 'upstream/master' into travis.osx