Fix #197: Account stays in connecting stage

Fix #197: Account stays in connecting stage

Move the purple_init_sipe_plugin call to installPlugin in order to ensure the plugin is initialized before adium calls configurePurpleAccount.

Also override purpleAccountName instead of manually setting username to prevent duplicate entries in accounts.xml for users who enter a login (one from account creation, one from account connection).  Need to figure out if there's a way to cleanup that second entry in accounts.xml in the future...