(MAINT) Bugfixes in host.exec and logger.

* Honor the :silent option in host.exec
* Many logging functions seem to try to pass positional parameters in to
  optionally_color but mistakenly flattened the list into a single argument.
  This made it impossible to choose whether or not to add a newline.
* Remove call to logger.notify with bogus arity. Seems like "args" probably
  becomes an empty array which made this method call okay previously. However,
  if there are no arguments in "*args" then no args get passed down to
  optionally_color, thus the arity of the original "*args" is preserved.

Signed-off-by: Wayne <wayne@puppetlabs.com>
(MAINT) Make retry_command output easier on the eyes.

Silent all the "on" commands by passing silent => true to the underlying
host.exec in the options map. Instead, handle console/logfile output for
retry_command manually. Should significantly reduce logfile size for
applications that make extensive use of retry_command, not to mention making
stdout more readable.

Signed-off-by: Wayne <wayne@puppetlabs.com>
Merge pull request #300 from waynr/feature/logging-improvements

Feature/logging improvements