Improve README on voicekit branch (#145)
Improve README on voicekit branch (#145)

I haven't restored the Travis badges as the build is failing on the
voicekit branch.
google/aiyprojects-raspbian,google/aiyprojects-raspbian,google/aiyprojects-raspbian,t1m0thyj/aiyprojects-raspbian,google/aiyprojects-raspbian,google/aiyprojects-raspbian,t1m0thyj/aiyprojects-raspbian