Update License

Fixes #2030
Fix asciidoc formatting of the base config options

Fixes #2035
Fix asciidoc link to string reference

Fixes #2038
More asciidoc fixes for base input and output

Fixes #2038
Fix formatting for word plain

Fixes #2038
Changes to generated docs and their templates.
Handling feedback for PR#2041
Force the uninstall of a plugin at install or update time.

It can happen we want to update a plugin that is a dependency for an other plugin
which will result in a warning and a manual action at uninstall phase of the install/update tasks
Since we are 100% sure in these cases that the plugin will be installed again we can force the uninstall part
not to alert us about it.

This solves the issue we otherwise would get:

Gem::DependencyRemovalException: Uninstallation aborted due to dependent gem(s)

Fixes #2034
Accept file and http URI in the `-f` flag.

This patch was slightly modified to make it merge correctly against
master
(original patch by @jsvd is #1873)

Closes #1873
Added a task to clean the vendor directory

Fixes #1981
Exposing the rake vendor:clean method to the help message

Fixes #1981
Rake way of deleting files

Fixes #1981