Transform settings methods into intstance ones
Instantiate Settings class
Create Settings initialization method reading from xml file
Move string defaults to getter methods
Handle string to boolean conversion for remaining parameters
Implement plugin descriptor (read-only)
Implement descriptor save operation
Promote into top level the Settings/Descriptor class

Move Settings into GitlabWebHookRootActionDescriptor. Replace uses of the
class with calls to get the plugin descriptor.
BUGFIX : protect against empty configFile
BUGFIX : wrong code to write to file
Implement true booleans for global configuration
BUGFIX : ruby file closing does not give a return code
Improve XML handling
Improve descriptor standarization
Add help files for global configuration
Hide parameters in UI when automatic project creation unchecked
BUGFIX : wrong way to set boolean default values
Merge pull request #25 from javiplx/feature/read_config_from_file

Implement global descriptor

Conflicts:
	models/services/get_jenkins_projects.rb