drop develop branch from CI files

we don't use a dev branch anymore

Author: spderosso

.appveyor.yml

@@ -34,4 +34,3 @@ test_script:
 branches:
   only:
     - master
-    - develop

.travis.yml

@@ -14,12 +14,10 @@ before_script:
 - git config --global user.name "travis-test"
 - git config --global user.email "travis@test.com"
 script:
-- nosetests --logging-level=WARN
-- nosetests gitless/tests/test_e2e.py --logging-level=WARN
+- python -m unittest discover gitless/tests
 branches:
   only:
   - master
-  - develop
 jobs:
   include:
   - stage: Pack snap

requirements.txt

@@ -1,4 +1,4 @@
-# make sure to update setup.py
+# make sure to update setup.py if you make any changes to this file
 
 argcomplete>=1.11.1
 pygit2==1.1.1  # requires libgit2 0.99 or 1.0

snap/snapcraft.yaml

@@ -13,6 +13,7 @@ description: |
   Git), you can always fall back on Git. And of course your coworkers you
   share a repo with need never know that you're not a Git aficionado.
 
+# Base snap for snapd that is based on Ubuntu 18.04
 base: core18
 
 grade: devel          # 'stable' for stable/candidate upload