[FIXED JENKINS-22924] - Allow the parameter specification from Jenkins CLI

The parameter takes the comma-separated list of values.

Signed-off-by: Oleg Nenashev <o.v.nenashev@gmail.com>

Conflicts:
	src/main/java/com/cwctravel/hudson/plugins/extended_choice_parameter/ExtendedChoiceParameterDefinition.java
Added .gitignore

Signed-off-by: Oleg Nenashev <o.v.nenashev@gmail.com>