Migrated nav drawer code into I2PActivityBase

.../i2p/android/i2ptunnel/activity/TunnelDetailActivity.java

...et/i2p/android/i2ptunnel/activity/TunnelListActivity.java

src/net/i2p/android/router/activity/AddressbookActivity.java

src/net/i2p/android/router/activity/HelpActivity.java

src/net/i2p/android/router/activity/I2PActivityBase.java

src/net/i2p/android/router/activity/I2PNavDrawerBase.java

src/net/i2p/android/router/activity/LicenseActivity.java

src/net/i2p/android/router/activity/MainActivity.java