Fix bug 872671 - Adapt to changes for ical.js Issue #85. r=lightsofapollo

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extra : rebase_source : 839977422a4973729f19ad488bf4571eb983e52e
Fix bug 872682 - Merge change "Remove obsolete componentFromString method reference" from upstream. r=lightsofapollo

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extra : rebase_source : 9d9461e131535f598950dcfac8e3afb82e55549d
Fix bug 872692 - Merge "Add a second subtractDate function that takes timezone difference into account" from upstream. r=lightsofapollo

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extra : rebase_source : db96567407db74f2ca9e627cfef6570fab213c6d
Fix bug 872694 - Merge "Add numericDayToIcalDay method" from upstream. r=lightsofapollo

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extra : rebase_source : 577a7b70f18fd606e460ba75b3697c77d88c67ae