Issue 130 - Add a README.md to the adblockplus repository

README.md

+Adblock Plus for Firefox
+========================
+
+Buildling
+---------
+
+### Requirements
+
+- [Python 2.x](https://www.python.org)
+- [The Jinja2 module](http://jinja.pocoo.org/docs)
+
+### Building the extension
+
+Run the following in the project directory:
+
+    ./build.py build
+
+This will create a build with a name in the form _adblockplus-1.2.3.4+.nnnn.xpi_. This file will contain the source code currently in the repository and all available locales.

[Felix Dahlke, 2014/07/18 11:55:23]

Decided against letting Emacs hard wrap here. I get the impression that's pretty
hard/annoying to work with for non-Emacs users :P

[Wladimir Palant, 2014/07/18 12:58:10]

Don't know, not really a big deal IMHO. The information you copied here is
outdated however, the current file name format is adblockplus-1.2.3.nnnn.xpi.

+
+### Installing the extension automatically
+
+To simplify the process of testing your changes you can install [Extension Auto-Installer](https://addons.mozilla.org/addon/autoinstaller). Assuming that Extension Auto-Installer is configured to use port 8888 (the default value), you can push your changes to this browser by running:
+
+    ./build.py autoinstall 8888
+
+The browser will be restarted automatically if necessary.

[Wladimir Palant, 2014/07/18 12:58:10]

Browser restart hasn't been necessary in a while now, probably better to say:
"The extension will update immediately, without requiring a browser restart."

+
+Running the unit tests
+----------------------
+
+To verify your changes you can use the existing [unit test suite](https://hg.adblockplus.org/adblockplustests). The unit tests are a separate extension that is installed in addition to Adblock Plus. You can either install the [existing unit test builds](https://adblockplus.org/devbuilds/adblockplustests) or clone the repository and create your own build. After installing the unit tests go to _chrome://adblockplustests/content/index.html_ to run the tests.