update node-webkit building instructions to reflect new, simplified usage via node-pre-gyp - refs #261

make sqlite3 library name configurable - enabling support for linking to sqlite3 variants like SQLCipher - refs #195

Build node-sqlite3 for node-webkit on Travis CI

The following `npm install` takes more than 3 seconds anyway; `xvfb` would already start before it becomes necessary for node-webkit.

Two packages not found → removing.

Found in “Search the contents of packages” at http://packages.ubuntu.com/ using “lucid” distribution (instead of default “saucy”).

This commit runs one `sudo apt-get -y install` for every package; otherwise each failure stops the whole installation process, but that makes the debugging painful (a test takes 13 minutes to run).

Used “Search the contents of packages” at http://packages.ubuntu.com/

As seen in http://www.maketecheasier.com/run-32-bit-apps-in-64-bit-linux/

Follow the following suggestion:

http://askubuntu.com/questions/363878/how-to-install-32-bit-matlab-in-ubuntu-64-bit/363879#363879

This commit also erases `sudo apt-get update --fix-missing` introduced in one of the previous commits, because it didn't help.

More magic.

xvfb recipe:
http://docs.travis-ci.com/user/gui-and-headless-browsers/#Using-xvfb-to-Run-Tests-That-Require-GUI-(e.g.-a-Web-browser)

sleep 3 recipe:
http://docs.travis-ci.com/user/gui-and-headless-browsers/#Starting-a-Web-Server

Commit Mithgol/node-pre-gyp@eaea6e159c9a052609cf93f0438cae17900f583b is now included in the node-pre-gyp's source used here.

A pull request (springmeyer/node-pre-gyp#36) is opened to land a partial fix for node-pre-gyp's validation process.

This commit uses a source branch of that pull request.

After this commit, node-pre-gyp's validator is expected to launch `nw` instead of `node-webkit` on Travis CI's Linux.

A former ENOENT error is expected to be replaced by a node-webkit's error when the engine realises it's given a node-sqlite3 module's JavaScript instead of some HTML5 application.