pyenv 0.4.0-20140602

Changes:

* python-build: Add new Anaconda/Anaconda3 releases; anaconda-2.0.0, anaconda3-2.0.0
* python-build: Add new CPython release; 2.7.7
* python-build: Update default setuptools version (3.6 -> 4.0)
* python-build: Respect environment variables of `CPPFLAGS` and `LDFLAGS`
* python-build: Support for xz-compressed Python tarballs