changed face tracker and photo demo to use API version 9

This allows those demos to run on gingerbread.  Note that multi-tracker
cannot use that API level, since it uses at least one newer API
feature (drawing ovals).

Change-Id: Ibc99a2bb8f1907737a9074e0c9d056cda2726fd1

Author: pm0733464

face/FaceTracker/app/build.gradle

@@ -6,7 +6,7 @@ android {
 
     defaultConfig {
         applicationId "com.google.android.gms.samples.vision.face.facetracker"
-        minSdkVersion 19
+        minSdkVersion 9
         targetSdkVersion 22
         versionCode 1
         versionName "1.0"

face/FaceTracker/app/src/main/AndroidManifest.xml

@@ -10,7 +10,7 @@
     <uses-permission android:name="android.permission.CAMERA" />
 
     <uses-sdk
-        android:minSdkVersion="11"
+        android:minSdkVersion="9"
         android:targetSdkVersion="21" />
 
     <application

face/photo-demo/app/build.gradle

@@ -6,7 +6,7 @@ android {
 
     defaultConfig {
         applicationId "com.google.android.gms.samples.vision.face.photo"
-        minSdkVersion 19
+        minSdkVersion 9
         targetSdkVersion 22
         versionCode 1
         versionName "1.0"

face/photo-demo/app/src/main/AndroidManifest.xml

@@ -6,7 +6,7 @@
     android:versionName="1" >
 
     <uses-sdk
-        android:minSdkVersion="11"
+        android:minSdkVersion="9"
         android:targetSdkVersion="21" />
 
     <application