Add initial assert helpers

Closes #110
Example of using assert.js
add "assert.js" to python, website runners too
Merge pull request #124 from domenic/asserts

Initial assert helpers
Merge pull request #127 from smikes/asserts

add "assert.js" to python, website runners too
Add assert.throws

Closes #57.
Add an example of using assert.throws
Merge pull request #131 from domenic/assert-throws

Add assert.throws
Move S9.9_A1/2 to proper locations

The with statement tests were novel, but the tests for
property accessors throwing errors for undefined & null
were duplicates with S11.2.1_A3_T4/5 respectively.
Reorganize ./test
Update python scripts for new paths
Merge pull request #132 from bterlson/rename

Clean up ./test directory
Move assert helper as well
Remove console/harness
Clean up website assets that are auto-generated
Fix packager.py for updated locations
Array.prototype.find no longer skips holes
Merge pull request #135 from juandopazo/find-holes

Array.prototype.find no longer skips holes
Rename `String.prototype.contains` to `String.prototype.includes`
initial tests of Array.prototpe.splice requiring settable "length"
add test of object with only "length" getter
*fix typo

per comments from @anba, thanks!
 * remove needless checks
 * add "splice" method

fix es5id