Changed the argument order for register_set.
Made Intel style operand ordering (dst <- src) the default behaviour.

* Moved Syntax::Intel.emit_operands into Syntax::ATT and reverse the
  dst <- src ordering back into src -> dst.
Version bump.
Made Intel syntax the default for Program#to_asm (closes #5).
Allow the width of MemoryOperands to be overrode.
Added ImmediateOperand#width.
Also made the default syntax intel for Program#assemble.
Specify that we want to use 32bit assembly for x86.

* This also has the side effect of reducing the size of assembled shellcode.
Updated the Examples.
Added a spec for Shellcode#assemble with att syntax.
Use ASCII encoding for Ruby 2.0.
Added Syntax::Common#emit_section.
Added Syntax::Common#emit_prologue.
Updated the README Example output.
Allow jruby-19mode to fail.
Unindent.
Allow byte/word/dword/qword casting methods to accept MemoryOperands.
Fixed a @param argument name.
Updated the ChangeLog for 0.2.0.
Use 1.9 Hash syntax in the README.