travis: add build status to README.
travis: add build status to README.

KaranToor/MA450,KaranToor/MA450,GoogleCloudPlatform/cloud-vision,csilzen/whatdoyousee,GoogleCloudPlatform/cloud-vision,KaranToor/MA450,KaranToor/MA450,GoogleCloudPlatform/cloud-vision,KaranToor/MA450,csilzen/whatdoyousee,csilzen/whatdoyousee,csilzen/whatdoyousee,GoogleCloudPlatform/cloud-vision,KaranToor/MA450,csilzen/whatdoyousee,csilzen/whatdoyousee,KaranToor/MA450,csilzen/whatdoyousee,csilzen/whatdoyousee,KaranToor/MA450,csilzen/whatdoyousee,GoogleCloudPlatform/cloud-vision