Changed install_plugins() to allow remote installation without local plugins

Line 953 in install_plugins() previously returned 0 if there were no local plugins to remotely install. In 3.07, this had no effect, but in 3.08 this causes the chain of functions performing the remote installation to fail prematurely without remotely installing aliases. 

Since bcvi can operate without plugins, this patch allows users without local bcvi plugins to perform remote installations.