travis: Don't push --all

We don't clean the remote directory, so if a branch runs a job it will
update all refs, and when another branch runs it will 'pass' without
doing a build as the git push says 'all refs up to date' and doesn't run
the post-receive hook.
travis: Fix the git push command

The previous commit removed a - from --force.
Refactoring the travis scripts to allow easier extension.
Fxing stuff for Joel's review.
Making a new branch for each travis build.
Merge pull request #84 from mithro/travis-exit-on-keyfile

Refactoring the travis scripts to allow easier extension.
Adding travis notification messages.
Adding travis environment to be sent over SSH.
Make it harder to accidently overwrite your travis ssh key.
Merge pull request #87 from mithro/travis-ssh-info

Adding travis environment to be sent over SSH.
Merge pull request #86 from mithro/travis-key-fix

Make it harder to accidently overwrite your travis ssh key.
Merge pull request #85 from mithro/travis-notify

Adding travis notification messages.
Add Travis CI status

Adds the Travis CI badge to the markdown, so it can be seen on our github page.
Allow custom path to Xilinx distribution in flash script, and default to the Atlys development board USB IDs for flashing.
Merge pull request #91 from miselin/allow-custom-xilinx-path

Allow custom path to Xilinx distribution in flash script, and default the Atlys development board USB IDs for flashing.