fix: update travis yml and fix coverage

.travis.yml

@@ -1,9 +1,9 @@
+cache:
+   npm: false
 language: node_js
 node_js:
-    - "6"
-    - "lts/*"                # Active LTS release
-    - "node"                 # Latest stable release
+    - "lts/*" # Active LTS release
+    - "node"  # Latest stable release
 before_install: 'make clean'
-install: 'make'
 script: 'make coverage'
 after_success: 'make report-coverage'

Makefile

@@ -131,7 +131,7 @@ coverage: $(NODE_MODULES) $(NYC) ## Run unit tests with coverage reporting. Gene
 
 .PHONY: report-coverage ## Report unit test coverage to coveralls
 report-coverage: $(NODE_MODULES) $(NYC) ## Run unit tests with coverage reporting. Generates reports into /coverage.
-	@$(NYC) report --reporter=text-lcov make test | $(COVERALLS)
+	@$(NYC) report --reporter=text-lcov | $(COVERALLS)
 
 
 .PHONY: clean