Refactor squeezambler image

Thanks for creating a squeezambler image Paul. You are very generous to
contriubute your time to towards this project. I have made some changes to the
image and this is quite a large pull request. Here is a summary of the main
points:

  * The second arg ($2) pass to the Docker container is a fastq file rather
    than a directory. I have therefore simplified the code to create the
    INPUT_FILE for a single fastq as opposed to iterating over a directory.
    This is the only required change to fit with the nucleotid.es API.

  * I have switched the base operating system to use debian wheezy rather than
    ubuntu. This saves around 100MB as the wheezy is smaller. I have installed
    the additional required libraries. A smaller image size makes it simpler to
    pull the image.

  * I have built squeezambler from source. The reason is allow kmer values upto
    128bp. Longer kmer values appear to have been very successful for velvet
    and ABySS so I believe the same could be true for squeezambler. I have
    added a careful proc entry to allow for longer kmer values and a higher
    depth cutoff. This however increases the image size as I have to install
    g++ and associated dependencies.