pyenv 0.4.0-20140404

Changes:

* pyenv: Reads only the first word from version file. This is as same behavior as rbenv.
* python-build: Fix build of Tkinter with Tcl/Tk 8.6
* python-build: Fix build problem with Readline 6.3
* python-build: Do not exit with errors even if some of modules are absent
* python-build: MacOSX was mispelled as MaxOSX in `anaconda_architecture`
* python-build: Use default `cc` as the C Compiler to build CPython
* python-build: Display value from `pypy_architecture` and `anaconda_architecture` on errors
* python-build: Remove old development version; 2.6-dev
* python-build: Update default setuptools version (3.3 -> 3.4.1)