fixed %f formatting issues in datetime.strptime and datetime.strftime

strptime acts diffrently depending on module it is called from (dateime
vs. time)
added very basic test_datetime.py
fixed cp34706 and cp32215
bug fix and changes for [date]time.strptime

fixed cp30047, invalid format/input combinations are not silently converted
Merge pull request #166 from paweljasinski/cp34706

fixed %f formatting issues in datetime.strptime and datetime.strftime
Disable Mono on all but .NET 4, as the others are broken.
added support for struct format strings of type bytes

(cherry picked from commit 3747d338239a7dd9a2860fb4506e8de51524fa08)