Sync ion up with shell from redox repository

git-subtree-dir: src
git-subtree-mainline: 69f5adad
git-subtree-split: 8270e514

This draft of the shell was written a while ago and was not used in
redox. After this commit I intend to merge the shell from redox into
this repository.

Fix ELF loader

Break things

Switch to using Result in io functions
Remove outdated ZFS scheme, as the ZFS app has new development

Conflicts:
	filesystem/apps/shell/main.rs

Fix compile issues

Fix compile issues

Real hardware

Add a terminal emulator

Avoid using _unused

Use the result information to catch bad commands before running them

Added Travis CI and Coveralls Badges

Cleaned up the syntax by using a match statement. Made it easier
to read and understand what was going on
On branch master
Changes to be committed:
	modified:   command.rs

Changes to be committed:
	new file:   .travis.yml

Ion now can execute single commands passed to it, including multiple flags and arguments. The result is an struct from which various things can be derived from, such as stderr and stdout. This can be expanded as more things are needed.

On branch master
Changes to be committed:
	new file:   src/command.rs
	modified:   src/lib.rs