Add ability to change to major version based on integer.

[fubarhouse]

I've got a use case where I need to simply switch to a different major version based on a Drupal core version in a bash script.

I've found that the particular way I need to work isn't available here, so I intend to add it in.

[fubarhouse]

So this feature now works for 'install' and 'use' commands which fits the purpose for the intention, but I'm going to expand this to the uninstall functions and potentially the reinstall function.

[fubarhouse]

I'm going to close this now, as reinstalling a fixed package in bulk would not add any value.

So now we can:

• install the latest version of a major version of our choosing
• uninstall all installed versions of a major version of our choosing
• set the default version to the latest available version installed of a major version of our choosing

I've got some ideas for change in the ansible roles, but this will add plenty of user cases to make use of the software. It will now be closed.