Adding a ssh step to before_install.

This means if SSH fails for any reason it will be a "Build Error" rather than
a "Test failure" message.
Fixing #81 - Force Makefile to use bash

We used PIPESTATUS which is bash only.
Merge pull request #82 from mithro/makefile-bash-fix

Fixing #81 - Force Makefile to use bash
Merge pull request #79 from mithro/travis-fix

Adding a ssh step to before_install.
Add Heart Beat Module

This adds an optional pulsing block to the output; both the passed
through signal and the recorded image.

The size of pulsing block can be changed by changing HB_length and
HB_width in hdl/misc/image_selector.vhd.

Heart beat can be switched on/off using switch 0 or by sending "SH" via
CDC. To achieve this hdl/misc/controller.vhd and hdl/hdmi2usb.vhd has
been modified.
Update gitignore

I did a build using ISE 14.4 on my Ubuntu machine. These ignores give me
a clean tree.
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.