dev-php/composer: version bump 1.3.1 -> 1.4.1.

dev-php/composer: version bump 1.3.1 -> 1.4.1.

This commit adds composer-1.4.1 and removes the old composer-1.3.1 at
the same time, allowing me to mess with the autoload.php in-flight. We
had one patch that was giving us trouble with v1.4.1, and this new
ebuild is an experiment to see if we can do away with it. Instead of
installing to /usr/share/php/Composer, the new v1.4.1 will install to
/usr/share/composer, and only create a symlink from /usr/bin/composer
to the "real" executable under /usr/share.

Since the executable loads everything via relative paths, having the
"real" executable under /usr/share (with the rest of its stuff) allows
composer to find what it's looking for out-of-the box, without us
having to point it towards our particular install location. As a
result, I've removed the one patch that did so, and I've updated
autoload.php with the new path.

Thanks are due to Guillaume Seren who did most of the prerequisite
work and stayed on top of the pull request and bug.

Gentoo-Bug: 613898
Closes: https://github.com/gentoo/gentoo/pull/4364

Package-Manager: Portage-2.3.3, Repoman-2.3.1