Remove resolver in project/build.sbt.

The Scala.js sbt plugin now in the standard repository for
sbt plugins, and can therefore be resolved by default.
Upgrade to Scala.js v0.3.
Remove obsolete .gitignore.
Move unit tests to package 'example'.

Instead of 'example.test'.
Upgrade to Scala.js v0.4.0 and its breaking changes.
Upgrade to Scala.js v0.4.1.
Upgrade to Scala.js v0.4.2.
Upgrade to Scala.js v0.4.3.
Remove now useless resolver.
Add Travis configuration.
Upgrade to Scala.js 0.4.4.
Upgrade to Scala 2.11.0.
Add HTML files to run the test suite with the HTML reporter.