Added Import for data bag, data bag item, environment,role and node

[terricain]

Adds support for importing the following resources

Also adds a validation function to ensure the server URL has a trailing slash, while it might be a go-chef issue it would be better to at least tell the user.

TODO:

• Add Server URL validation
• Add Data Bag import
• Add Data Bag Item import
• Add Environment import
• Add Node import
• Add Role import
• Update Docs to warn about trailing slash
• Update chef_environment example
• Update chef_node example
• Update chef_role example
• Add import info to chef_data_bag_item
• Add Data Bag import test
• Add Data Bag Item import test
• Add Environment import test
• Add Node import test
• Add Role import test

Fixes #8
Fixes #15
Fixes #26

[terricain]

@kmoe or @appilon does someone mind reviewing this?