Merge branch 'fix_ci' into 'master'

install curl before using

See merge request !6

.gitlab-ci.yml

 image: continuumio/miniconda:latest
 
 before_script:
+  - conda install -y curl
   - curl -OLk https://raw.githubusercontent.com/openpathsampling/openpathsampling/master/devtools/conda_ops_dev_install.sh
   - bash conda_ops_dev_install.sh
   - conda install -y nose coverage