Python3 migration for Sublime Text 3

I tried out DocBlockr in Sublime Text 3.  Sublime Text 3 is using python3 so several things didn't work.  I ran the 2to3 migration tool which took care of most items.  Then edited the outputWidth function in JsdocsCommand.alignTags, renamed
str to input and string.replace to str.replace.  Seems to work properly for me know.

I don't really expect you to merge this, just trying to help.  The Package Control project has a python3 branch for it's Sublime Text 3 compatible version, so that's why I named this branch that.

Cheers.  Thanks for the plugin!