Add tests
Remove timezone attributes => only GMT
Update readme
Add lubridate dependency
Add forze_tz to POSIX conversion
Merge pull request #18 from SthlmR/issue-13-forze_tz

Issue 13 forze tz
Update tests
Merge branch 'issue-13'
Merge branch 'master' of https://github.com/SthlmR/Coldbir

Conflicts:
	DESCRIPTION
	R/0-constants.r
	inst/tests/tests.r