'unregister' command is not implemented

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
.gitignore

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
[loader] is_reloadable property

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
[server] loader sometimes can't be touched

Provider does not rely on weak_ptr because corresponding loader can be
destroyed only after provider is removed. Also, loader can't be
reloaded if it is not reloadable.

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
[api] supplying server interface to provider

Currently server interface is used to send "reload" event to server when
e.g. provider configuration is changed

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>