Added smb_enumshares.
Updated smb_enumshares.rb
Updated.
Updated.
Modified a few things based on suggestions.
Changed default VERBOSE option to false.
This fixes a few things, see commit message for more info

This commit fixes the following:

1. Not handling eval_host()'s nil file return value, which can causes
   a NoMethodError at runtime due to various conditions.
2. Renames datastore option VERBOSE to ShowFiles to pass msftidy
3. Avoids overwriting datastore options directly to pass msftidy
Land #3569 - Updated smb_enumshares to support spidering