Fixes to resample over DST boundaries
closes #5172 
closes #8744
closes #8653 
closes #9173
closes #9468
closes #8794

fixes all issues but one attached to #5172.  There were several issues as mentioned by my comments in the master list.  They are:
1. Offset classes were not working properly over DST boundaries.  I added flags on the class to handle specially.
2. `normalize_date` does not work with DST change dates as the tz offset is not adjusted. `normalize` is added to Timestamp as discussed in #8794 (I don't like how this was done, but it seemed the easiest rather than duplicating lots of code in `tslib.date_normalize`.
3. `_adjust_dates_anchored` was not localizing properly once times were adjusted. 
