Refactor grunt tasks about portainer

[raphaelquati]

It would be nice to compile on Windows.

[deviantony]

@raphaelquati I'd accept a PR to have a multi-arch build system ;)

[adrianfalleiro]

@deviantony Currently testing a refactored Gruntfile. Will submit a PR in the next week or so

[deviantony]

@adrianfalleiro awesome ! Keep me posted or join me on Slack you need info or have any questions: http://portainer.io/slack/

[eine]

I split the refactorization related modifications from #938 and I opened a new issue with these: #939.

• Tasks with parameters/functions are used.
• build<Platform><Arch>Binary tasks are replaced with a single one.
• grunt-if dependency is dropped.

[eine]

I tried to follow the same approach with run, runSwarm, etc. but the plugin (watch) does not support any kind of function or parameter: https://github.com/gruntjs/grunt-contrib-watch

However, I slightly reduced the verbosity, replacing the task list with a single task.