change vertexFor to findOrCreateVertexFor

- vertexFor method has a side effect of creating new vertex if there
  is no vertex with given data
- findOrCreateVertexFor explains this intent more clearly
make the rename of jruby-jars.gem to maven convention work [skip ci]
use jruby from build to run ruby scriplets [skip ci]
let it work with non snapshot versions as well [skip ci]
[IR] Work around incorrect scope depths in AST local var nodes

* AST doesn't seem to be implementing shadowing properly and
  sometimes has the wrong depths which screws up variable access.

  Check scope depths for 'a' in the closure in the following snippet:
      "a = 1; foo(1) { |(a)| a }"
  In "(a)", it is 0 (correct), but in the body, it is 1 (incorrect)

* So, we implement shadowing in IRClosure by searching for an
  existing local var from depth 0 and upwards and setting
  scopeDepth to not what AST gives us but based on where we
  found the variable.

* We could either decide to leave this shadowing implementation in
  place or rely on AST (in which case this has to be fixed in
  the AST node).

* This patch fixes the output for this snippet and eliminates
  mspec failures for spec/ruby/language/block_spec.rb

def foo(x); yield x; end
a = 5
puts foo(2) { |(a)| a }
[IR] Minor: clarify comment from previous commit (75cb53aba)
Merge pull request #1028 from prathamesh-sonpatki/rename-vertex-for

change vertexFor to findOrCreateVertexFor
minimal work to remove 1.8 parser
Do not wrap arg arrays in RubyArrays prematurely

This refactor makes it easier for deeper calls to determine exactly
what their args looks like (when transformed into a RubyArray too soon,
it was hard for yielders to tell if you have multiple args,
or one array arg)

This lets us clean up a few places which were adding extra logic to deal
with that ambiguity, and positions us to start applying
RubyProc.prepareProcArgs more centrally (all proc calls need that logic
applied, but it is currently not enforced in some places)
Merge pull request #1200 from dmarcotte/arg-arrays

Do not wrap arg arrays in RubyArrays prematurely
Huzzah...Annotation for marking which methods are acceptable to be used by Java native extensions...now to start annotating those methods...
Minimum to remove 1.9 parser
Remove vestigial RubyParserPool.  Next possible re-use scenario would be to put Parser instance on TC
Softlink jruby to jruby.bash instead of hard copy.