[gmime] Attempt to fix the Travis CI build

[Jeffrey Stedfast <fejj src gnome org>]

commit df3dc72728d2c616ecccb280c159c27f736dedee
Author: Jeffrey Stedfast <jestedfa microsoft com>
Date:   Fri Mar 3 09:22:05 2017 -0500

    Attempt to fix the Travis CI build

 .travis.yml |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/.travis.yml b/.travis.yml
index a5fd5fa..036d7f9 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,10 @@
 language: c
 compiler:
   - gcc
+sudo: required
+before_install:
+  - sudo apt-get -qq update
+  - sudo apt-get install -y gtk-doc gpgme-dev
 script:
   - ./autogen.sh
   - ./configure --disable-mono && make && make check