avoid http redirect to download estudio
test script: build image before rspec

This takes a few minutes on first build, but
subsequent builds use the cache and are fast.
fix test failure due to upstream rubocop changes

* bbatsov/rubocop@ff167d8f changed Rubocop -> RuboCop
* require min version of rubocop to ensure bundle has the above commit
latest rubocop now prefers backticks over %x

upstream rubocop now recommends to use backticks instead of %x
rspec/mocha now requires symbol for mock_with

Resolves error:

    Unknown mocking framework: "mocha".
    Pass a module or one of [:rspec, :flexmock, :rr, :mocha, :nothing]
run spec_standalone to support old and current rake tasks

Latest bundle seems to not invoke :spec_standalone from :spec,
so invoke it directly. This ensures the harness runs regardless
of which bundle is installed.
add tools for working with mercurial repositories
update all packages in base image at build-time
add host and dig commands to devenv
add ftp and tftp clients

These are useful for testing other services.
use the "semi-official" fedora 20 base image