Refactor connection errors

Makes command.py a lot more readable.
Move "Can't find fig.yml" error into errors.py
Indent string literals
Merge pull request #114 from orchardup/refactor-errors

Extract error text into errors.py
Update Orchard description
Update Orchard description
Vendorise six.py

Because pyinstaller adds an old version to the path:

http://www.pyinstaller.org/ticket/773
Fix Dockerfile reference URL in docs
Alternate fig file can be specified with -f
Add custom link names (Closes #72)
Fix links related test
Add link names test
Provide option to remove volumes in `fig rm`
Merge pull request #124 from marksteve/delete-volume

Provide option to remove volumes in `fig rm`
Merge pull request #113 from orchardup/alternate-fig-file

Alternate fig file can be specified with -f
Merge pull request #120 from marksteve/link-name

Add custom link names (Closes #72)
Remove six from requirements

It was vendorised in 75c430635b46de090165bcc5140050fe0f1dd56d
Fix tests importing six
Documentation: Include notes on mapping ports

When mapping ports as strings there is an issue with the way YAML parses
numbers in the format "xx:yy" where yy is less than 60 - this issue is
now included in the documentation.

This fixes #103
Add script to build an OS X binary