Use `os.execvpe` with `run`, fix `shell`

Use `exec` to replace the envdir process with the child process (fixes #20).

This commit also fixes `(env)shell` to behave properly when `Ctrl-C` is
pressed in the subprocess (apparently caused by using os.setsid).
Make the authors a list.
add Daniel and myself to authors
rewrite the tests to mock os.execvpe to avoid replacing the test runner process
Merge pull request #31 from ticosax/add-myself

add Daniel and myself to authors
Merge pull request #30 from ticosax/use-os-exec

Use os exec
Use a shorter timeout with `test_keyboard_interrupt`
Add changelog entry for 0.7
actually we are the 10th now.
Merge pull request #34 from ticosax/changelog

Changelog entry for 0.7
new realease for 0.7
Merge pull request #35 from ticosax/new-release-0.7

new realease for 0.7
prepare next version
Merge pull request #36 from ticosax/back-to-dev

prepare next version
Bump version to 0.7 for docs
Added Python 3.4 to travis test matrix.
Added Appveyor config.
Removed 2.6 and 3.2 from Appveyor test matrix because they aren't installed there.
Added AppVeyor build status image.
Detect the shell on Windows better.