Allows use of IDictionary<string, object> as parameter objects.
I'm assuming that the && was a mistake, and that this logic should
handle both of the types equally well.
Also allows .NET 3.5 to use the IDictionary case.

Avoid type-name conflicts causing cache conflicts (makes the cache per-T; also avoids locking on the happy-path)

Depends on Issue 174
https://code.google.com/p/dapper-dot-net/issues/detail?id=174

https://code.google.com/p/dapper-dot-net/issues/detail?id=57

An AmbiguousMatchException is encountered when the Type.GetProperty(String, BindingFlags) method is used and there are multiple indexers on the type, so it was replaced with a call to Type.
GetProperty(String, BindingFlags, Binder, Type, Type[], ParameterModifier[]).