Add StartActivity - landing page of baby monitor

The StartActivity is the first activity which will be launched
in the baby monitor, and in the future will list the two main
options: become a monitor or a listener.

res/values/dimens.xml

@@ -0,0 +1,7 @@
+<resources>
+
+    <!-- Default screen margins, per the Android Design guidelines. -->
+    <dimen name="activity_horizontal_margin">16dp</dimen>
+    <dimen name="activity_vertical_margin">16dp</dimen>
+
+</resources>

res/values/strings.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <string name="app_name">BabyMonitor</string>
+    <string name="action_settings">Settings</string>
+
+</resources>

res/values/styles.xml

@@ -0,0 +1,20 @@
+<resources>
+
+    <!--
+        Base application theme, dependent on API level. This theme is replaced
+        by AppBaseTheme from res/values-vXX/styles.xml on newer devices.
+    -->
+    <style name="AppBaseTheme" parent="android:Theme.Light">
+        <!--
+            Theme customizations available in newer API levels can go in
+            res/values-vXX/styles.xml, while customizations related to
+            backward-compatibility can go here.
+        -->
+    </style>
+
+    <!-- Application theme. -->
+    <style name="AppTheme" parent="AppBaseTheme">
+        <!-- All customizations that are NOT specific to a particular API-level can go here. -->
+    </style>
+
+</resources>