Change Coverity Scan branch to use 'dev' instead of master.

We don't want to run out of scan tokens for every README update.  This
also means the introduction of a new workflow.  All new development must
be staged to the dev branch before being merged to master.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

.travis.yml

@@ -14,9 +14,9 @@ addons:
   coverity_scan:
     project:
       name: "troglobit/libuev"
-      description: "libuEv | Simple asynchronous event loop for Linux."
+      description: "libuEv | Simple event loop for Linux"
     notification_email: troglobit@gmail.com
-    build_command:      "make"
-    branch_pattern:     master
+    build_command: "make"
+    branch_pattern: dev
 
 script: make