more guideline updates

i2p2www/pages/site/get-involved/guides/dev-guidelines.html

@@ -111,7 +111,9 @@ Run 'ant findbugs' to learn more.
 We require Java 7 to build and run I2P.
 Do not use Java 8 classes or methods anywhere.
 Do not use Java 7 or 8 classes or methods in embedded subsystems (core, router, mstreaming, streaming, i2ptunnel),
-as Android and embedded applications require only Java 6.
+as Android and embedded applications require only Java 6. All classes must be available in Android API 9.
+Java 7 language features are acceptable in these subsystems if supported by the current version
+of the Android SDK and they compile to Java 6-compatible code.
 {%- endtrans %}</li>
 <li>{% trans -%}
 Explicitly convert between primitive types and classes;
@@ -129,6 +131,10 @@ Don't use String.getBytes(). Use DataHelper.getUTF8() or DataHelper.getASCII().
 <li>{% trans -%}
 Don't use String.split(). Use DataHelper.split().
 {%- endtrans %}</li>
+<li>{% trans -%}
+Use {} for all for and while blocks, even if only one line.
+If you use {} for either the if, else, or if-else block, use it for all blocks.
+{%- endtrans %}</li>
 </ul>
 
 <h3>{{ _('Licenses') }}</h3>