AURORA-565: update top level README with instructions on bootstrapping and running initial test
AURORA-565: update top level README with instructions on bootstrapping and running initial test

Updates README with basic instructions to get started with Apache Aurora.

Preview: https://github.com/jfarrell/incubator-aurora/tree/AURORA-565

Bugs closed: AURORA-565

Reviewed at https://reviews.apache.org/r/23317/

rdelval/aurora,medallia/aurora,rdelval/aurora,protochron/aurora,shahankhatch/aurora,rosmo/aurora,rdelval/aurora,wfarner/aurora,crashlytics/aurora,thinker0/aurora,mkhutornenko/incubator-aurora,thinker0/aurora,wfarner/aurora,mkhutornenko/incubator-aurora,medallia/aurora,mschenck/aurora,kidaa/aurora,medallia/aurora,protochron/aurora,thinker0/aurora,mkhutornenko/incubator-aurora,shahankhatch/aurora,thinker0/aurora,wfarner/aurora,protochron/aurora,shahankhatch/aurora,kidaa/aurora,kidaa/aurora,crashlytics/aurora,kidaa/aurora,medallia/aurora,protochron/aurora,apache/aurora,crashlytics/aurora,rosmo/aurora,rosmo/aurora,rdelval/aurora,mkhutornenko/incubator-aurora,mschenck/aurora,thinker0/aurora,kidaa/aurora,crashlytics/aurora,wfarner/aurora,protochron/aurora,crashlytics/aurora,rdelval/aurora,crashlytics/aurora,mkhutornenko/incubator-aurora,mschenck/aurora,apache/aurora,protochron/aurora,apache/aurora,apache/aurora,rosmo/aurora,shahankhatch/aurora,medallia/aurora,apache/aurora,rosmo/aurora,mschenck/aurora,shahankhatch/aurora,wfarner/aurora,mschenck/aurora,rosmo/aurora,wfarner/aurora,apache/aurora,kidaa/aurora,shahankhatch/aurora,thinker0/aurora,rdelval/aurora,medallia/aurora,mschenck/aurora