support for FxA web flow (bug 1033694)
add in contributing.md
Merge pull request #538 from andymckay/contributing

add in contributing.md
Commit from Mozilla Verbatim by user sara.todaro@mozillaitalia.org.: 111 of 111 strings translated (0 fuzzy).
Merge pull request #534 from washort/fxa

support for FxA web flow (bug 1033694)
preserve localStorage for SIM logout (bug 1042381)
Merge pull request #539 from kumar303/sim-logout

preserve localStorage for SIM logout (bug 1042381)