Ruby: Use base64 encoding for  :pack_simple_arrays option (to_simple_value)

Uses base64 encoded strings as return value for to_simple_value, in case :pack_simple_arrays option is used.

Base64.strict_encode64 is available from ruby 1.9.2, it is needed, bacause Base64.encode64 fills the String with additional newlines at teh end or after 40 chars (default in http headers, but not wanted here).
Yes. It can. Now just think of the two alternatives in front of you:
 - add information that you already have (and is *one integer*)
 - create, for each language that is going to demarshal this, code that looks what the pack code is, infers the size in bytes of each element and computes the element size from there 

You do know what is the alternative I perfer.