Merge pull request #97 from pbitty/config_compat

extract old vagrant version compatibility code into util method
splits hostnames across many lines, as Windows doesn't seem to like more than 8 on a line
Merge pull request #103 from thematthopkins/windows_hostnames_length_fix

splits hostnames across many lines

Closes #60.
remove unnecessary HostsFile include
isolate core HostsFile module code into its own class
remove redundant config argument from Updater initializer
extract Updater class into its own file
migrate UpdateHost action to use Updater class
migrate UpdateGuest action to use Updater class
migrate provisioner to use Updater class
migrate UpdateAll action to use Updater class and remove hosts_file.rb