[BRUNDLE-2629] mudar ec2-axis para aceitar fallback para on-demmand

Desenvolvedores: Matheus / Jorge
Merge branch 'master' of gitlab:brundle/ec2-cloud-axis-plugin

Conflicts:
	src/main/java/hudson/plugins/ec2/OnDemandInstanceProvider.java
Refactoring to allow reuse of instance provisioning
Adding input parameters to enable reallocation to OnDemand
Adding Task to manage orphan slaves
Refactoring slave provider to use instance provider
Refactoring to allow multiple instance providers
Merge branch 'master' of gitlab:brundle/ec2-cloud-axis-plugin
Merge branch 'master' of /home/git/repositories/matheus.moraes/ec2-cloud-axis-plugin