Enable perfboot.py to install APKs before measurement.

This CL adds --apk-dir option, which specifies the directory
that contains APK files to be installed before measuring
boot time.

BUG: 22207911
Change-Id: Ifeacf34c779248686443a9ef02485272c140a456
diff --git a/adb/device.py b/adb/device.py
index b6eaad6..a15675b 100644
--- a/adb/device.py
+++ b/adb/device.py
@@ -170,8 +170,12 @@
         out, _ = p.communicate()
         return self._parse_shell_output(out)
 
-    def install(self, filename):
-        return self._simple_call(['install', filename])
+    def install(self, filename, replace=False):
+        cmd = ['install']
+        if replace:
+            cmd.append('-r')
+        cmd.append(filename)
+        return self._simple_call(cmd)
 
     def push(self, local, remote):
         return self._simple_call(['push', local, remote])