Relaxed dependency requirements for mtl and parsec to avoid conflict with http package
Support for network >= 2.6
Nix support
Travis support
Tweaked readme to add Travis badge
Amended as per Ollie requests
Merge branch 'stefanjaax-pull-request'
Merge branch 'bump-network' of https://github.com/adinapoli/iCalendar into adinapoli-bump-network-master

Conflicts:
	iCalendar.cabal
Merge branch 'adinapoli-bump-network-master'
Merge branch 'nix-support' of https://github.com/adinapoli/iCalendar into adinapoli-nix-support
Merge branch 'travis-support' of https://github.com/adinapoli/iCalendar into adinapoli-travis-support
Merge branch 'adinapoli-travis-support'