Update minimum version requirement

[1951FDG]

Only one issue, you uploaded the extension, but I believe you forgot to set the minimum version requirement to version 1.7 of brackets. On Brackets 1.6, the extension downloaded will fail to run.

engines.brackets (encouraged) - which Brackets versions the extension is compatible with, specified as a string in semver range format. Typically >= 0.xx, where "xx" is a Brackets sprint number (this says the extension won't run on older builds before sprint "xx", but it's assumed to be compatible with all future builds of Brackets)