Attempt to fix build error on Travis

See https://travis-ci.org/CatalystCode/project-fortis/jobs/346867514

Author: c-w

project-fortis-interfaces/travis/ci.sh

@@ -6,9 +6,7 @@ pushd "$(dirname $0)/.."
 
 err=0
 
-if [ ! -d node_modules ]; then
-  npm install
-fi
+npm install
 
 if ! ./node_modules/.bin/eslint --max-warnings=0 src *.js; then
   err=1

project-fortis-services/travis/ci.sh

@@ -6,9 +6,7 @@ pushd "$(dirname $0)/.."
 
 err=0
 
-if [ ! -d node_modules ]; then
-  npm install
-fi
+npm install
 
 if ! ./node_modules/.bin/eslint --max-warnings=0 src *.js; then
   err=1