v4 changelog

Changelog.md

+## v4 (01/20/2012)
+
+Features:
+
+* Updated to virtualenv v1.7 and patched pip v1.2.
+* Actually activate created virtualenv within compile process.
+* Use distribute instead of deprecated setuptools.
+* Automatically destroy and rebuild corrupt virtualenvs.
+* Refactor django and pylibmc detection.
+
+Bugfixes:
+
+* Fixed `package==dev` in requirements with patched pip embedded within virtualenv. Patch upstreamed.
+* Minor curl/rm flag fixes (thanks, contributors!)
+
+
 ## v3 (12/07/2011)
 
 Bugfixes:
 
 * Better django setup.py injection.
 
+
 ## v2 (11/15/2011)
 
 Features:
@@ -14,6 +31,7 @@ Bugfixes:
 
 * Detect when virtualenv is checked in and alert user.
 
+
 ## v1 (10/01/2011)
 
-* Conception.
\ No newline at end of file
+* Conception.