Platform specific properties in manifest and copy assets folder

[zicsus]

What does this PR do?

1. Add platform specific properties to manifest. Now you can use chrome and firefox to define browser specific properties in manifest. Please note that chrome is used as default configuration.
2. Copies whole assets folder to build dir except locales as they are processed separately.

Where to start reviewing?
gulpfile.js

Related Issues?
n/a

Caveats?
Builds file in same folder irrespective of build config. This can be an issue for parallel testing in Firefox and Chrome.

Reviewers?
@nkrusch

[nkrusch]

@zicsus I have merged this but I have a concern about changing the assets output directory name because it will break any existing project that assumes a different directory name. Thoughts of how to address:

• make major version increment or
• make the directory name configurable
• or can do both actually

[zicsus]

What do you mean different directory name?
Only thing that assets compiled was imgs, right?

[nkrusch]

Yes it compiles images only, but currently it does

assets/{images} -> dist/icons

after this change it will be

assets/{images} -> dist/assets

[zicsus]

Major version increment is better step IMO because configuration will still break existing project. With major release we can lay down all the changes.