Testing!

[andyli]

This adds very basic testing:

• .hx file should be recognized as Haxe file
• build should work when a .hx file is opened and there is a build.hxml file

Before merging, please go to TravisCI and AppVeyor to switch on this repo.

[clemos]

Looks awesome, though I haven't had time to look into it last week-end. I will surely do it this week.

[clemos]

Finally... it works :D Sorry for the delay, it was really easy indeed :) Thanks so much !