Add option no_message_tag

This option is used to indicate that the user does not wish to encapsulate the message in a 'message tag'.
Support no_message_tag option

This option indicates that the user does not want to encapsulate the message in a 'message tag'.
Added WSDL fixture for no_message_tag test.

Added test case for :no_message_tag global option.

This option appears to be a workaround for a bug
in either the wsdl parser or the building of the XML
response message. I am not entirely sure what the issue
is but the :no_message_tag option solves the problem
I ran into when using savon with the 3PLCentral XML/Soap
client APIs.
Added WSDL fixture for no_message_tag test.

Added test case for :no_message_tag global option.

This option appears to be a workaround for a bug
in either the wsdl parser or the building of the XML
response message. I am not entirely sure what the issue
is but the :no_message_tag option solves the problem
I ran into when using savon with the 3PLCentral XML/Soap
client APIs.
Merge branch 'master' of github.com:etteyafed/savon
Merge remote-tracking branch 'origin/pr/584'

Conflicts:
	spec/savon/options_spec.rb