basic travis-ci integration

What is left to do: go to https://travis-ci.org → authenticate with GitHub → change under user profile (top right corner) to Secretchronicles account (left edge) → click the switch of SMC repo to activate. done.

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 * builds currently run between 4 and 6 minutes
 * gcc 4.6.3 and clang 3.4 are used (newer versions would be possible, though)
 * project is configured and installed (without special configuration)