migrate COT to support Travis-CI container infrastructure

[glennmatthews]

We should be able to enhance the speed of our Travis-CI builds by migrating to the newer infrastructure: http://docs.travis-ci.com/user/migrating-from-legacy/

In order to accomplish this migration, instead of using 'cot install-helpers' to install the helper tools (which requires 'sudo', which is only available in the legacy infra), we need replicate the helper installtion into our .travis.yml.

Specifically we need to use addons.apt.packages in our travis.yml (http://docs.travis-ci.com/user/migrating-from-legacy/#Adding-APT-Packages) to install all of the packages that are available through apt-get, then build and locally install any that are not.

apt-get packages:

• make
• gcc
• genisoimage (travis-ci/apt-package-whitelist#593)
• qemu-utils (travis-ci/apt-package-whitelist#553)
• zlib1g-dev

packages to build from source:

• fatdisk
• vmdktool

[glennmatthews]

see also travis-ci/apt-package-whitelist#588 (genisoimage), travis-ci/apt-package-whitelist#483 (qemu)

[glennmatthews]

may be able to use xorriso as an alternative to genisoimage/mkisofs ?