Fixes validations in Chef 13 for LWRP attributes

[cattywampus]

The :kind_of types set for several LWRPs are Strings but their default values are nil. In Chef13, there is apparently a strict validation enforcing the types of the assigned values or default values of an attribute match their type. The affected resources and attributes are:

• install_feature resource - name property
• download_feature resource - name and directory properties

The default values for name properties have been removed since names are required for resources anyway, they should never be nil. The directory property is now defaulted to the node[:wlp][:base_dir] since that is what has happening behind the scenes in the provider anyway.

Fixes #51