Support for binary deployment

default to installing from pre-built binaries: build from source now with 'npm install --build-from-source'

remove && in engins

added a section that explains rebuilding sqlite3 for node-webkit

Code improvements

Fix installation instructions in README.md

Pre-increment/decrement can be more efficient than post-increment/decrement for non-primitives.

a couple of minor changes in README

Node's website http://nodejs.org/ is hyperlinked instead of the engine's GitHub repository.

A local hyperlink to the “INSTALLING” section is introduced instead of less detailed `npm install sqlite3`.

create “INSTALLING” section in README for the most simple instructions

Currently the most simple `npm install sqlite3` is buried in the most deep bottom of the “BUILDING” section. And the instructions for building the `master` branch immediately precede it.

This commit creates a separate “INSTALLING” section (placed before “BUILDING”) containing only the most simple instructions.

A new method of building the `master` branch is introduced. The user's system won't even need `git` for that because a tarball is downloaded by npm from GitHub.

A message about the necessity of meeting node-gyp's requirements is given.

display npm package version

The https://badge.fury.io/ service is used to display the latest version of the project's npm package.

A quick look at the GitHub's project page may then tell any user if an upgrade is available (without visiting https://npmjs.org/package/sqlite3 for this purpose).

A hyperlink to https://npmjs.org/package/sqlite3 is still available so that the package's version can be confirmed whenever the user feels that https://badge.fury.io/ service is less trusted (or if https://badge.fury.io/ is down, though the latter I haven't experienced yet).

configure Travis CI services

run test/support/createdb.js before testing

drop devDependencies from package.json

Fix developmentseed/node-sqlite3#169

Drop step@0.0.4 from devDependencies

Extend the timeout

Currently the `devDependencies` value in `package.json` lists `"step": "0.0.4"`, but it does not seem that the `step` module is used anywhere.