fixes `bundle install` step from the README, currently broken by https://github.com/hashicorp/vagrant-spec/issues/41
```
~/src/vagrant-libvirt $ bundle install
....
Fetching git://github.com/hashicorp/vagrant-spec.git
fatal: Needed a single revision
Revision master does not exist in the repository git://github.com/hashicorp/vagrant-spec.git. Maybe you misspelled it?
```
Works fine now on my workstation with the new name:
```
Using vagrant-spec 0.0.1 from git://github.com/hashicorp/vagrant-spec.git (at main@b6b56c8)
Bundle complete! 10 Gemfile dependencies, 73 gems now installed.
```
Latest vagrant depends on a vagrant-spec release containing a more
recent dependency on childprocess than is supported for earlier releases
of vagrant.
Adjust dependencies to pin to the specific release of vagrant-spec if
the request version of vagrant is 2.2.7 or older.
Does not attempt to handle the situation where a version is specified
that cannot be parsed.
While it would be useful to test against newer versions of 2.2.x, it
appears this encounters a bug in upstream vagrant when installing in
dev mode see https://github.com/hashicorp/vagrant#11293
Therefore limit latest 2.2.x released version tested against to 2.2.4.
Add some basic spec tests for the WaitTillUp action class to lay some
foundations. Utilize vagrant-spec pinned to a known working commit for
tests to pass consistently until they provide releases.
Requires updating some of the rspec libraries and includes
sharedcontext.rb from the jantman/vagrant-r10k project on github.
