Fix failing travis builds for tests and docs

* Upgrade/install setuptools as installing charm would complain about
missing setuptools
* Use Python 3.7

.ci/travis-install.sh

@@ -4,10 +4,12 @@ set -e -x
 
 pip install --upgrade pip
 
-# will not be needed for flake8
-git clone https://github.com/JHUISI/charm.git
-cd charm && ./configure.sh && make install
-cd ..
+if [ "${BUILD}" != "flake8" ]; then
+    pip install --upgrade setuptools
+    git clone https://github.com/JHUISI/charm.git
+    cd charm && ./configure.sh && make install
+    cd ..
+fi
 
 if [ "${BUILD}" == "tests" ]; then
     pip install -e .[test]

.travis.yml

@@ -1,5 +1,7 @@
 language: python
-python: 3.6
+sudo: required
+dist: xenial
+python: 3.7
 
 env:
   global:

setup.py

@@ -27,7 +27,6 @@
     'ecdsa',
     'zfec>=1.5.0',
     'gipc',
-    'charm-crypto @ https://github.com/JHUISI/charm.git@dev',
     'coincurve',
 ]