Add e2e tests

[nicolaferraro]

This is built on top of #756

Fixes #693

This adds a series of e2e tests that should verify (if travis works) the most important functionalities, e.g.:

• installation using different options
• building kits
• running integrations correctly (checking the logs for success)

The most important thing is that most of the tests start from user commands (interacting directly with kamel CLI).

[nicolaferraro]

Ok, this runs in 14 mins (compared to previous version, that was 9 minutes and doing nothing useful, this seems nice).

This includes switching to Camel 3 (#756), so I think I can close #756 .