plugins: changed member order of PluginInfo

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
plugins: use big contructor for making PluginInfo instances

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
core: enable exceptions

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
plugins: added PluginInfoReader service

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
plugins: added PluginRepository class

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
plugins: remove unused signals

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>