Install tox inside the conda environment.

Signed-off-by: Tim 'mithro' Ansell <tansell@google.com>

.travis.yml

diff --git a/.travis.yml b/.travis.yml
index dabf64f..a361894 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,17 +1,14 @@
-language: python
-
-matrix:
-  include:
-    - python: 3.7
-      env: TOXENV=py37
+language: minimal
 
 install:
-  - . prepareenv.sh
-  - conda activate yosys-env
+  - source prepareenv.sh
   - source .github/travis/check_license.sh
   - source .github/travis/check_python_script.sh
 
-script: tox
+script:
+  - conda activate yosys-env
+  - which tox
+  - tox
 
 notifications:
   email: false

conf/environment.yml

diff --git a/conf/environment.yml b/conf/environment.yml
index 08fb66b..c7a801f 100644
--- a/conf/environment.yml
+++ b/conf/environment.yml
@@ -3,3 +3,6 @@
   - symbiflow
 dependencies:
   - yosys
+  - pip:
+    - tox
+    - flake8

prepareenv.sh

diff --git a/prepareenv.sh b/prepareenv.sh
index 5193fa0..1c89efe 100755
--- a/prepareenv.sh
+++ b/prepareenv.sh
@@ -8,7 +8,6 @@
 #
 # SPDX-License-Identifier:	ISC
 
-pip install tox
 wget https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh -O miniconda.sh
 bash miniconda.sh -b -p $HOME/miniconda
 source "$HOME/miniconda/etc/profile.d/conda.sh"
@@ -17,3 +16,4 @@
 conda install -q setuptools
 conda update -q conda
 conda env create --file conf/environment.yml
+conda activate yosys-env