This is to implement
nodejs#7676 (comment)

* make `--with-intl=none` the default
 * Download, verify (md5), unpack ICU's zip if not there
 * update docs
* add a test

There's a "list" of URLs being used, but right now only the
first is picked up. The logic works something like this:

* if there is no directory `deps/icu`,
 * if no zip file (currently `icu4c-54_1-src.zip`),
  * download zip file (icu-project.org -> sf.net)
 * verify the MD5 sum of the zipfile
  * if bad, print error and exit
 * unpack the zipfile into `deps/icu`
* if `deps/icu` now exists, use it, else fail with help text

Also:
* refactor some code into tools/configure.d/nodedownload.py
* add `intl-none` option for `vcbuild.bat`

To rebuild `deps/icu-small` - (not currently checked in)
```
bash tools/icu/prepare-icu-source.sh
```

Reduce space by about 1MB with ICU 54 (over without this patch).
Also trims a few other source files, but only conditional on the exact ICU
version used. This is to future-proof - a file that is unneeded now may
be needed in future ICUs.

Usage:
 * `--with-icu-source=/path/to/my/other/icu`
 * `--with-icu-source=/path/to/icu54.zip`
 * `--with-icu-source=/path/to/icu54.tgz`
 * `--with-icu-source=http://example.com/icu54.tar.bz2`

this fixes srl295/node#11

this lets you choose which locales are used in the `small-icu` case

Example:

  configure --with-intl=small-icu  --with-icu-locales=tlh,grc,nl

Note that the unit test tests/simple/test-intl.js hasn't been updated
yet.

(Also note that as of this writing, neither Klingon nor Ancient Greek
are in upstream CLDR data. Serving suggestion only.)

This completely and totally fixes #10 

With dependency fix as suggested by @misterdjules
fixes srl295/node#12

This was suggested by @misterdjules as it causes test failures.
With this fix, "out" is no longer created on windows and

      python tools/test.py simple

.. can run properly.

…ad-python-26

build: make nodedownload.py work with Python 2.6 👍

build: fix ICU support build on SmartOS (and probably solaris-gcc also)

Respond to review comments from @misterdjules:

* Remove the prepare-icu-source.sh mechanism for creating
  an embedded deps/icu-small as per
  7cb4aad - it was not
  currently used and thus deadwood.

* Updated README.md to clarify some of the options:
  that 'none' is the default for --with-intl, and that
  --with-icu-source works with 'small-icu'

* clarified the test-intl.js test case

* cleaned up and added documentation in configure and in nodedownload.py

Instead of downloading ICU if missing from `deps/icu`, just print a warning
unless either `--download=all` or `--download=icu` is set.

Add some generic scaffolding in case other modules end up in the same boat
in the future.

It's harmless to pass `--download=xyzzy`, so, future proof
(at least until some xyzzy dependency is integrated).

build: i18n: Don't auto-download ICU unless --download=all

Thanks @trevnorris for taking a look.

With this change, `make distclean` will
delete these items, which aren't in the source repo:
* `icu_config.gypi`
* `deps/icu` - the ICU source tree
* `deps/icu-tmp` - the temporary download/unpack work area
* `deps/icu4c*.tgz deps/icu4c*.zip` - ICU source tarballs