Adding mozilla libraries required by Firefox interop test.

third_party/mozinfo/README.md

+Throughout [mozmill](https://developer.mozilla.org/en/Mozmill)
+and other Mozilla python code, checking the underlying
+platform is done in many different ways.  The various checks needed
+lead to a lot of copy+pasting, leaving the reader to wonder....is this
+specific check necessary for (e.g.) an operating system?  Because
+information is not consolidated, checks are not done consistently, nor
+is it defined what we are checking for.
+
+[MozInfo](https://github.com/mozilla/mozbase/tree/master/mozinfo)
+proposes to solve this problem.  MozInfo is a bridge interface,
+making the underlying (complex) plethora of OS and architecture
+combinations conform to a subset of values of relavence to 
+Mozilla software. The current implementation exposes relavent key,
+values: `os`, `version`, `bits`, and `processor`.  Additionally, the
+service pack in use is available on the windows platform.
+
+
+# API Usage
+
+MozInfo is a python package.  Downloading the software and running
+`python setup.py develop` will allow you to do `import mozinfo`
+from python.  
+[mozinfo.py](https://github.com/mozilla/mozbase/blob/master/mozinfo/mozinfo.py)
+is the only file contained is this package,
+so if you need a single-file solution, you can just download or call
+this file through the web.
+
+The top level attributes (`os`, `version`, `bits`, `processor`) are
+available as module globals:
+
+    if mozinfo.os == 'win': ...
+
+In addition, mozinfo exports a dictionary, `mozinfo.info`, that
+contain these values.  mozinfo also exports:
+
+- `choices`: a dictionary of possible values for os, bits, and
+  processor
+- `main`: the console_script entry point for mozinfo
+- `unknown`: a singleton denoting a value that cannot be determined
+
+`unknown` has the string representation `"UNKNOWN"`. unknown will evaluate
+as `False` in python:
+
+    if not mozinfo.os: ... # unknown!
+
+
+# Command Line Usage
+
+MozInfo comes with a command line, `mozinfo` which may be used to
+diagnose one's current system.
+
+Example output:
+
+    os: linux
+    version: Ubuntu 10.10
+    bits: 32
+    processor: x86
+
+Three of these fields, os, bits, and processor, have a finite set of
+choices.  You may display the value of these choices using 
+`mozinfo --os`, `mozinfo --bits`, and `mozinfo --processor`. 
+`mozinfo --help` documents command-line usage.