Add status/error checks during ONOS startup
Add status/error checks during ONOS startup

We check for:
- process exits
- log ERRORs
- log WARNings
- low memory

Also added a "status" CLI command to check for exits
and errors.

Change-Id: I6e65fe49619e338f1827fc616ca52a82de7ba470

Shashikanth-Huawei/bmp,opennetworkinglab/onos,mengmoya/onos,opennetworkinglab/onos,LorenzReinhart/ONOSnew,Shashikanth-Huawei/bmp,LorenzReinhart/ONOSnew,y-higuchi/onos,VinodKumarS-Huawei/ietf96yang,sdnwiselab/onos,oplinkoms/onos,maheshraju-Huawei/actn,kuujo/onos,mengmoya/onos,mengmoya/onos,oplinkoms/onos,Shashikanth-Huawei/bmp,VinodKumarS-Huawei/ietf96yang,osinstom/onos,maheshraju-Huawei/actn,oplinkoms/onos,sdnwiselab/onos,kuujo/onos,kuujo/onos,Shashikanth-Huawei/bmp,osinstom/onos,opennetworkinglab/onos,LorenzReinhart/ONOSnew,sdnwiselab/onos,oplinkoms/onos,donNewtonAlpha/onos,kuujo/onos,maheshraju-Huawei/actn,osinstom/onos,oplinkoms/onos,osinstom/onos,opennetworkinglab/onos,y-higuchi/onos,gkatsikas/onos,mengmoya/onos,gkatsikas/onos,sdnwiselab/onos,VinodKumarS-Huawei/ietf96yang,donNewtonAlpha/onos,maheshraju-Huawei/actn,VinodKumarS-Huawei/ietf96yang,VinodKumarS-Huawei/ietf96yang,gkatsikas/onos,kuujo/onos,maheshraju-Huawei/actn,Shashikanth-Huawei/bmp,LorenzReinhart/ONOSnew,opennetworkinglab/onos,y-higuchi/onos,opennetworkinglab/onos,sdnwiselab/onos,donNewtonAlpha/onos,kuujo/onos,kuujo/onos,osinstom/onos,oplinkoms/onos,y-higuchi/onos,gkatsikas/onos,donNewtonAlpha/onos,oplinkoms/onos,gkatsikas/onos,sdnwiselab/onos,donNewtonAlpha/onos,gkatsikas/onos,y-higuchi/onos,mengmoya/onos,LorenzReinhart/ONOSnew