Fix *occassional* npm install failures on Travis CI
Fix *occassional* npm install failures on Travis CI

https://github.com/travis-ci/travis-ci/issues/2244#issuecomment-55473829
mentions creating the npm directory manually as a temporary workaround

clever-crow-consulting/otm-core,recklessromeo/otm-core,RickMohr/otm-core,RickMohr/otm-core,clever-crow-consulting/otm-core,recklessromeo/otm-core,maurizi/otm-core,clever-crow-consulting/otm-core,recklessromeo/otm-core,maurizi/otm-core,clever-crow-consulting/otm-core,maurizi/otm-core,RickMohr/otm-core,recklessromeo/otm-core,RickMohr/otm-core,maurizi/otm-core