Proxy support when fetching remote files

[vitorbrandao]

This PR gives support for networks behind a proxy.

Proxy support is accomplished by setting a stream context to the file_get_contents() call.

Usage:

$browscap = new Browscap('/tmp');

// auto-detect proxy settings from the environment
$browscap->autodetectProxySettings();

// or, set proxy settings manually
$browscap->addProxySettings('proxy.example.com, 3128, 'http', 'myuser', 'mypass');

// check defined stream context options
$options = $browscap->getStreamContextOptions();

// remove proxy settings
$browscap->clearProxySettings()

Also, some phpunit tests are added as well as a travis config file for automatic testing on travis servers.

[GaretJax]

Exceptional! Great pull request, thank you noisebleed

[vitorbrandao]

No problem. I just love your project, very helpful. Thanks ;)

You'll need a travis service hook to "light up" your new shiny travis button. See > here < how to do it.

[GaretJax]

Done... I guess we'll have to wait now ;)

(so the mail about a failing test I got today was because of you :D )

[vitorbrandao]

Yep, sorry about that!

You can push the Test Hook button in the admin/travis page to trigger the build manually. Afterwards, on every push, the repo is automatically tested and the build status updated. The travis logo reflects the status of the master branch.

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