break apart date_utils.js
add some moment helpers for Jasmine testing
new tests for ambiguous moments, moment construtors, moment range querying
improvements and bugfixes to FullCalendar's MomentJS extensions

notably we have no side effects on the Moment prototype anymore. we subclass
parse ISO8601 date strings without date-of-month as first-of-month
misc comments
different behavior when end-time equals nextDayThreshold. tests
fix broken updateEvent method
bump to 2.0.0-beta2