Fixed how conda installed in travis-ci

Author: gavinmdouglas

.travis.yml

@@ -7,7 +7,15 @@ python:
   - "3.6-dev"  # 3.6 development branch
 
 install:
-  - pip install conda
+  # Install miniconda
+  - wget https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh -O miniconda.sh;
+  - bash miniconda.sh -b -p $HOME/miniconda
+  - export PATH="$HOME/miniconda/bin:$PATH"
+  - hash -r
+  - conda config --set always_yes yes --set changeps1 no
+  - conda update -q conda
+  
+  # Install PICRUSt2
   - conda env create -f  picrust2-env.yaml
   - source activate picrust2
   - pip install --editable .