Bump golang version to 1.11

Makefile

@@ -14,7 +14,6 @@ help:
 	@echo '    make build           Build yq binary.'
 	@echo '    make install         Install yq.'
 	@echo '    make xcompile        Build cross-compiled binaries of yq.'
-	@echo '    make snap            Build a snap package of yq.'
 	@echo '    make vendor          Install dependencies using govendor.'
 	@echo '    make format          Run code formatter.'
 	@echo '    make check           Run static code analysis (lint).'
@@ -65,10 +64,6 @@ xcompile: check
 	@find build -type d -exec chmod 755 {} \; || :
 	@find build -type f -exec chmod 755 {} \; || :
 
-.PHONY: snap
-snap:
-	snapcraft
-
 .PHONY: install
 install: build
 	${DOCKRUN} go install