Upgrade to Puppet 4.x

[Imesh Gunaratne]

Currently WSO2 Puppet Modules use Puppet 3.x. We need to upgrade this to Puppet 4.x:
https://docs.puppet.com/release_notes/

[Dilan Ariyaratne]

Closing this issue since we are already working on moving our modules to Puppet 5.x [1][2].
[1] #45
[2] #46