elixir: use buildroot-generated erl

Fix the make build environment so that buildroot-generated tools are
used. This fixes the problem where the elixir build would invoke the
Erlang release found in the path or error out if none was found.
Add travis configuration file; missing apt-get

This adds a travis configuration for continuously building the
nerves-sdk. Travis found a missing apt-get install line, so this adds it
too.
mmccopy: bump version to 1.0.2
README.md: Add travis build status
bbb/fwtool.config: Fix typo in rootfs count

The rootfs block count was too big. This didn't break anything since the
rootfs is only partially used, but it should be right. fwtool currently
doesn't validate that there's no overlap between partitions.
ag150: add x86 support and ag150 target

Many common files were refactored to avoid duplication with the
Beaglebone Black.
Updates to support building out of tree

This cleans up paths so that building in Erlang project directories
works for x86. There are still hardcoded things to the Beaglebone is the
naming, but this fixes the functional aspects.
Enable ext4 in base ag150 image
Update buildroot patches (mtools and syslinux)

This also pulls in several upstream changes.
erlang-fwtool: bump to v0.1.1
Pull in various updates and improvements for AG150
alix: new board
alix: pull in fixes from ag150 work
Add mtools patch to fix iconv usage
Switch bzImage filenames to 8.3 versions

Not necessary, but it cleans up the directory listings when using mdir.