Machinecoin: Added demo keystore credentials

Related to https://github.com/Gitju/bitcoin-wallet/issues/1
Will be removed later.
Lets me build the whole project on a fresh system a lot faster as because I just have to setup a keystore under ~/.machinecoinkeystore/keystore.jks with IntelliJ IDEA 13 and therefore I use "android" and "androidpassword" as credentials.
The appstore app has to be build with a real and unique one.

wallet/pom.xml

@@ -194,6 +194,8 @@
                             <arguments>
                                 <argument>-sigalg</argument><argument>MD5withRSA</argument>
                                 <argument>-digestalg</argument><argument>SHA1</argument>
+                                <argument>-keystore</argument><argument>~/.machinecoinkeystore/keystore.jks</argument>
+                                <argument>-storepass</argument><argument>androidpassword</argument>
                             </arguments>
                         </configuration>
                     </execution>