Make projects case insensitive when using multimapproxy

[FrankyBoy]

Right now the project names are treated case sensitive, so my.mapproxy.com/Foo_Bar is not the same as my.mapproxy.com/foo_bar. I think it would make sense to treat these project names case insensitive instead, simply because it can prevent much debugging effort and gnashing of teeth when not being careful during configuration.