Add git similarity option to upload.py

Add git similarity option to upload.py

This change is to help tweak the rename heuristic in git so the file history is properly presented in Rietveld.

[iannucci, 2012-10-01 18:45:56]

This is the upload.py piece of the git_similarity patch here:
https://chromiumcodereview.appspot.com/10945002/

This needs to be merged into default and chromium before the other patch can
land :)

[M-A, 2012-10-01 18:51:21]

cc: ML

This change is to help tweak the rename heuristic in git so the file history is
properly presented in Rietveld.

lgtm

[iannucci, 2012-10-01 23:01:51]

On 2012/10/01 18:51:21, M-A wrote:
> cc: ML
> 
> This change is to help tweak the rename heuristic in git so the file history
is
> properly presented in Rietveld.
> 
> lgtm

M-A, could you land this? I don't have commit access.

Thanks :)