Check in the vendor directory

Travis seems to be having issues pulling deps, so we'll have to check in
the vendor directory and prevent the makefile from trying to regenerate
it normally.

vendor/github.com/gogo/protobuf/AUTHORS

@@ -0,0 +1,15 @@
+# This is the official list of GoGo authors for copyright purposes.
+# This file is distinct from the CONTRIBUTORS file, which
+# lists people.  For example, employees are listed in CONTRIBUTORS,
+# but not in AUTHORS, because the employer holds the copyright.
+
+# Names should be added to this file as one of
+#     Organization's name
+#     Individual's name <submission email address>
+#     Individual's name <submission email address> <email2> <emailN>
+
+# Please keep the list sorted.
+
+Sendgrid, Inc
+Vastech SA (PTY) LTD
+Walter Schulze <awalterschulze@gmail.com>