Aliasing safe_load to load

[btoews]

• Aliasing YAML::safe_load to YAML::load.
• Adding orig_load, orig_load_file for original functionality

There are so few use cases for unmarshaling ruby objects with YAML that we should make the "safe" behavior default.

[dtao]

I like this idea—esp. as it makes this gem particularly useful for projects where YAML.load might already be used in some places. Just add a dependency on "safe_yaml" and you're done: no more arbitrary code execution vulnerability.

The only thing I'd change is the name 'orig_load'; I think something like 'unsafe_load' would be clearer. I'll merge this for now; but what are your thoughts on that?