Changes default sourceType of js extraction from 'script' to 'module'…

[IShotTheSheriff]

…. It fixes issue #144 with parsing ES6 code.

[rubenv]

Could you add a unit test that demonstrates why this is needed? Just to make sure we don't break it again in the future.

[sbrandtb]

I tried locally. It may fix the issues you mentioned regarding imports, but it doesn't solve the issues with using double colons

[IShotTheSheriff]

@rubenv sure I've just added test cases for both export and import features of ES6.
@sbrandtb yea I was targeting only import/export problem as it stopped whole files from being parsed. I can try to fix double colons issue in another PR if you can provide me with some example of what's wrong.

[rubenv]

Excellent patch! Merged.

[rubenv]

Release v2.2.2 of angular-gettext-tools and grunt-angular-gettext.

Thanks a lot @IShotTheSheriff!