Add OEX compatibility to conversion process + ship minified versions of the JS library files

[richtr]

With these commits a developer can, if they wish to, zip up a .nex converted output directory as a .oex file and this .oex file containing the .nex code will run successfully in Opera versions <= 12.15 (in addition to being able to run as a .nex file in Opera > 12.15 of course). ;)

This pull request supersedes pull request #8 (if you merge this fix then we can discard pull request #8 since it includes the same commits as this super-set pull request).

[miketaylr]

OK, I was in the wrong branch when I got those failures. So now I'm going to delete that comment for realz. The actual failures are:

So basically we didn't want the config.xml to be there before, but we want it now @richtr? I can update the tests if that's the case.

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FAIL: test_nex_files (tests.nex.TestNEX)
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Traceback (most recent call last):
  File "/Users/miket/dev/oex2nex/oex2nex/tests/nex.py", line 39, in test_nex_files
    self.assertNotIn("config.xml", nex.namelist())
AssertionError: 'config.xml' unexpectedly found in ['config.xml', 'hello.png', '__MACOSX/', '__MACOSX/._hello.png', 'inline_script_index_1.js', 'oex_shim/operaextensions_background.min.js', 'index.html', 'oex_shim/operaextensions_popup.min.js', 'popup.html', 'manifest.json', 'oex_shim/popup_resourceloader.html', 'oex_shim/popup_resourceloader.js']

======================================================================
FAIL: test_nex_files_from_dir (tests.nex.TestNEX)
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Traceback (most recent call last):
  File "/Users/miket/dev/oex2nex/oex2nex/tests/nex.py", line 53, in test_nex_files_from_dir
    self.assertNotIn("config.xml", nex.namelist())
AssertionError: 'config.xml' unexpectedly found in ['config.xml', 'hello.png', 'inline_script_index_1.js', 'oex_shim/operaextensions_background.min.js', 'index.html', 'oex_shim/operaextensions_popup.min.js', 'popup.html', 'manifest.json', 'oex_shim/popup_resourceloader.html', 'oex_shim/popup_resourceloader.js']

----------------------------------------------------------------------
Ran 78 tests in 20.401s

FAILED (failures=2)