Mark current version as 2.1.1.git

Signed-off-by: Rafał Malinowski <rafal.malinowski@corp.bluecherry.net>
Implemented Version class

Signed-off-by: Rafał Malinowski <rafal.malinowski@corp.bluecherry.net>
Use Version class for comparing versions

Signed-off-by: Rafał Malinowski <rafal.malinowski@corp.bluecherry.net>
Added unit tests for Version class

Signed-off-by: Rafał Malinowski <rafal.malinowski@corp.bluecherry.net>
Moved checking updates to separate file

Signed-off-by: Rafał Malinowski <rafal.malinowski@corp.bluecherry.net>