Fixed #58.

Initial attempt to fix this issue,

1. When assemblies are being registered, find PCL ones and add their profile paths to search paths.
2. Suppress `CopySecurityDeclarations` exceptions as PCL ones do not have security declarations.

Both changes are experimental as I only run through initial testing on simple cases.
`Mono.Collections.Generic.Collection` does not have an indexer that accepts name. Meanwhile, such attributes are generated directly by the compiler and should not vary much.

I am going to send another revision and see how to safely query the property by name, though.