Update README
Update README

- Remove instructions to install the JDK, as we now use the
  Bazel-provided remote JDK.
- Formatting (wrap at 80 chars column)

Change-Id: I446d64a5e2910427b09937ff7adbe84991c70bcd

gkatsikas/onos,gkatsikas/onos,gkatsikas/onos,oplinkoms/onos,oplinkoms/onos,oplinkoms/onos,oplinkoms/onos,opennetworkinglab/onos,gkatsikas/onos,opennetworkinglab/onos,gkatsikas/onos,opennetworkinglab/onos,oplinkoms/onos,opennetworkinglab/onos,opennetworkinglab/onos,gkatsikas/onos,opennetworkinglab/onos,oplinkoms/onos,oplinkoms/onos