remove iml file from source control

We added this file in the gitignore a while ago, but it was already
versioned. It has not been modified since 2015, it is safe to completely
remove it.

Change-Id: I5fc498375d48d4ed1413943c0b07741aa116f312

ring-android/ring-android.iml

-<?xml version="1.0" encoding="UTF-8"?>
-<module external.linked.project.id="ring-android" external.linked.project.path="$MODULE_DIR$" external.root.project.path="$MODULE_DIR$" external.system.id="GRADLE" external.system.module.group="" external.system.module.version="unspecified" type="JAVA_MODULE" version="4">
-  <component name="FacetManager">
-    <facet type="java-gradle" name="Java-Gradle">
-      <configuration>
-        <option name="BUILD_FOLDER_PATH" value="$MODULE_DIR$/build" />
-        <option name="BUILDABLE" value="false" />
-      </configuration>
-    </facet>
-  </component>
-  <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_1_7" inherit-compiler-output="true">
-    <exclude-output />
-    <content url="file://$MODULE_DIR$">
-      <excludeFolder url="file://$MODULE_DIR$/.gradle" />
-    </content>
-    <orderEntry type="inheritedJdk" />
-    <orderEntry type="sourceFolder" forTests="false" />
-  </component>
-</module>
\ No newline at end of file