- NPE fix on signed udpates

apps/i2psnark/java/src/org/klomp/snark/UpdateHandler.java

apps/i2psnark/java/src/org/klomp/snark/UpdateRunner.java

...2psnark/java/src/org/klomp/snark/web/I2PSnarkServlet.java

...e/java/src/net/i2p/router/update/PluginUpdateHandler.java

...java/src/net/i2p/router/update/UnsignedUpdateChecker.java

...java/src/net/i2p/router/update/UnsignedUpdateHandler.java

...console/java/src/net/i2p/router/update/UpdateHandler.java

...rconsole/java/src/net/i2p/router/update/UpdateRunner.java

core/java/src/net/i2p/I2PAppContext.java

router/java/src/net/i2p/router/RouterContext.java