Fix travis builds (#73)

* Fixes Travis builds by installing cvxpy via conda

.travis.yml

@@ -9,7 +9,7 @@
 
 env:
   global:
-    - CONDA_DEPS="pip flake8 nose coverage pytest numpy scipy matplotlib seaborn pandas h5py" PIP_DEPS="coveralls pytest-cov codecov pathlib travis-sphinx boto"
+    - CONDA_DEPS="pip flake8 nose coverage pytest numpy scipy matplotlib seaborn pandas h5py cvxpy nbconvert entrypoints" PIP_DEPS="coveralls pytest-cov codecov pathlib travis-sphinx boto"
 
 matrix:
   include:
@@ -25,30 +25,33 @@ matrix:
     #     - MINICONDA_URL="https://repo.continuum.io/miniconda/Miniconda3-latest-MacOSX-x86_64.sh"
     - os: linux
       python: 2.7
-      env:
-         - PYTHON_VERSION=2.7
-         - MINICONDA_URL="https://repo.continuum.io/miniconda/Miniconda2-latest-Linux-x86_64.sh"
     - os: linux
       python: 3.5
-      env:
-         - PYTHON_VERSION=3.5
-         - MINICONDA_URL="https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh"
-
+    - os: linux
+      python: 3.6
+    - os: linux
+      python: 3.7
 
 before_install:
 - export MINICONDA=$HOME/miniconda
 - export PATH="$MINICONDA/bin:$PATH"
 - hash -r
-- echo $MINICONDA_URL
-- wget $MINICONDA_URL -O miniconda.sh;
+- if [[ "$TRAVIS_PYTHON_VERSION" == "2.7" ]]; then
+    wget https://repo.continuum.io/miniconda/Miniconda2-latest-Linux-x86_64.sh -O miniconda.sh;
+  else
+    wget https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh -O miniconda.sh;
+  fi
+- export PYTHON_VERSION=$TRAVIS_PYTHON_VERSION
 - bash miniconda.sh -b -f -p $MINICONDA;
-- conda config --set always_yes yes
-- conda update conda
+- source "$MINICONDA/etc/profile.d/conda.sh"
+- conda config --set always_yes yes --set changeps1 no
+- conda update -q conda
 - conda info -a
-- conda install nbconvert
-- conda install entrypoints
-- conda config --add channels conda-forge
-- conda install python=$PYTHON_VERSION $CONDA_DEPS
+- conda config --append channels conda-forge
+- conda config --append channels cvxgrp
+- conda config --set channel_priority strict
+- conda create -n testenv python=$PYTHON_VERSION $CONDA_DEPS
+- conda activate testenv
 - travis_retry pip install $PIP_DEPS
 
 install: