Add fields and field annotations to jruby.
Use ordered hash map to ensure fields are defined in order specified.
Fix issues with java_signature for parameters.
Better fix.
Update testing doc.
Add field annotation.

This allows a seralization objects to be constructed in ruby.
Formatting.
Correct readme.
Fixing hashing consistency across JVM instances.

Several of the core JRuby classes calculate hash codes based on java or ruby
object ids. This doesn't produce consistent hashing across JVM instances, which
is needed for distributed frameworks. For example, Hadoop uses hashCode values
to distribute keys from the map phase to the same reducer task (partitioning).

This commit adds hashCode (and ruby's hash method) implementations for
RubyBoolean, RubyNil, and RubySymbol. RubyBoolean and RubyNil simply return
static, randomly-generated hashCode values that are hard-coded. This replaces
the default java Object#hashCode.

For RubySymbol, the previous implementation of hashCode returned the symbol's
id, which could be different depending on the order in which symbols are
created. This updates it to calculate a hashCode based on the raw symbolBytes
like the RubyString implementation, but with a RubySymbol-specific seed and
without the encoding addition for 1.9. This value is calculated when symbols
are instantiated so the performance impact should be minimal.

This commit also adds a RubyInstanceConfig setting and CLI option for
consistent hashing, jruby.consistent.hashing.enabled, which controls whether
the Ruby runtime's hash seeds (k0 and k1) are generated randomly. When set to
true, they are set to static values. These hash seeds are used to hash
RubyString objects, so this will make string hash codes consistent across JVMs.

(later commit...)

Updating hashCode implementations.

Per discussion on the last commit's pull request [1], updating the
implementations of hashCode for RubyNil and RubyBoolean. Now the hashCode
behavior for nil and booleans will only change when consistent hashing is
enabled. Adds a hashCode instance variable to RubyBoolean and RubyNil that is
set in the constructor to the Object#hashCode value (using
System.identityHashCode) or a static value.

[1]: https://github.com/jruby/jruby/pull/590
IO.copy_stream should handle objects that respond to read or write. Fixes #437
Fix string concatenation with a number as per rubyspec behaviour.

Following https://github.com/tychobrailleur/jcodings/commit/8536b4fdeecf3dec31ca868803654b3ab7829915, the incorrect behaviour of String#concat with
a number was made obvious by throwing an EncodingException.  MRI changes
the encoding of the String if the concatenated codepoint is within
ASCII-8BIT range, and throws a RangeError otherwise.
IO.binwrite should accept options hash
Refactored directed graph specs
20: Don't include kwargsRest as final arguments to rest arg
20: More kwargs fixing block kwargs don't classcastexception (icky fix until 9k)
Allow Process::Status to be used as an integer and be returned as an exit status
20: take this as far as possible without serious changes for kwargs
* Reuse the to_i method for to_int
Fix and refactor slightly GC and GC::Profiler.
Merge pull request #728 from prathamesh-sonpatki/directed_graph_specs

Refactored directed graph specs