rebaseline.py: add --bugs and --unreviewed flags

tools/tests/rebaseline/output/marked-unreviewed/output-expected/gm-expectations/Test-Android-GalaxyNexus-SGX540-Arm7-Debug/expected-results.json

 {
   "expected-results": {
     "3x3bitmaprect_565.png": {
       "allowed-digests": null, 
       "ignore-failure": false
     }, 
     "3x3bitmaprect_8888.png": {
       "allowed-digests": null, 
       "ignore-failure": false
     }, 
@@ skipping 16 matching lines @@
       ], 
       "ignore-failure": false
     }, 
     "imageblur_565.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           3359963596899141322
         ]
       ], 
+      "bugs": [
+        1234, 
+        5678
+      ], 
       "ignore-failure": false, 
+      "notes": "notes_content", 
+      "reviewed-by-human": false, 
       "unknown-extra-field": "make sure that rebaseline.py maintains this unknown field within a record whose allowed-digest IS modified"
     }, 
     "imageblur_8888.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           4217923806027861152
         ]
       ], 
-      "ignore-failure": false
+      "bugs": [
+        1234, 
+        5678
+      ], 
+      "ignore-failure": false, 
+      "notes": "notes_content", 
+      "reviewed-by-human": false
     }, 
     "shadertext3_8888.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           3713708307125704716
         ]
       ], 
-      "ignore-failure": false
+      "bugs": [
+        1234, 
+        5678
+      ], 
+      "ignore-failure": false, 
+      "notes": "notes_content", 
+      "reviewed-by-human": false
     }, 
     "xfermodeimagefilter_pdf.png": {
       "allowed-digests": null, 
       "ignore-failure": false
     }, 
     "xfermodes_pdf.png": {
       "allowed-digests": [
         [
           "bitmap-64bitMD5", 
           9151974350149210736
         ]
       ], 
       "ignore-failure": false
     }
   }
 }