Added isSameDay

Checks if a date is the same day as a passed date.
Changed param type and used toDateString instead
Timezone tests changed to take into account daylight saving time. 2 tests were failing, because offset between UTC and London timezone is not constant due to DST(0 with DST off, 1 with DST on).
One from strings tests was failing due to inconsistent declaring DateTime COOKIE constant across multiple PHP versions. Check here http://3v4l.org/Pu6TS#v520
Self keyword changed to static in all method calls, but all constants references were left with self keyword. It is due to the fact that there are constants, but also because static keyword is not allowed in compile time constants. Therefore static keyword can't be used to declare another constant or method argument.
Fixing condition in testToCOOKIEString() method.
Merge pull request #121 from doubleking/master

Method calls with self keyword changed to static. Also few tests fixes.
Released 1.9.0
Added getter for weekOfMonth. Returns the occurence of the day of the week within the month, e.g. returns 2 if the date is the second Friday in the month.
Create minimal and maximal possible date
Fixed issue with isPast() returning true for now()
Updated testing
CS fixes
Merge pull request #145 from GrahamCampbell/cs

CS Fixes
Merge pull request #144 from GrahamCampbell/travis

Updated Testing
Merge pull request #142 from RyanNielson/fix_ispast_issue

Fixed issue with isPast() returning true for now()
Updated isPast implementation to use static rather than self.
Fixed up download link and removed dummy padding.
Fixed merged conflicts
Merge pull request #127 from itised/weekOfMonth

Added getter for weekOfMonth