AURORA-299: use system thrift if available
AURORA-299: use system thrift if available

Updates gradle bootstrapThrift to use a system installed Thrift if available
and if it is the same version we are currently using.

Testing Done:
ran build with and without Thrift installed

Bugs closed: AURORA-299

Reviewed at https://reviews.apache.org/r/20246/

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