Fixing Check_Type bug and forcing 2-argument mode for all Hadoop::DFS::FileSystem.delete calls

This pull request addresses a bug in the typechecking bug via what appears to be the idiomatic Ruby boolean detection method, comparing the value to the statically-defined Qtrue typedef; this has been tested to work successfully.

Additionally, as we are not yet using variable arguments, we are forcing two arguments to Hadoop::DFS::FileSystem.delete and three arguments to Hadoop::DFS::FileSystem.copy for proper operation.

Let me know what you think, and thanks for the consideration!