This change adds support for builds that target armhf/arm64 configurations alongside the current amd64 builds, which should bring support for single-board computers such as Raspberry Pi and Odroid into the core.

Due to the Travis white-list freeze, the configuration for this process uses the 14.04 Trusty Tahr container, and uses the 16.04 Xenial Xerus repositories on ports.ubuntu.com to prepare a toolchain that contains the necessary dependencies for ARM cross-compilation.

The arm64 configuration above will also use the same armhf dependencies as those builds for things like ripgrep.  This should not pose an issue for users due to the backwards compatibility for ARMv8.

Dummy edit to trigger a final Travis CI build to test before issuing pull request

Adding deb and rpm packages for linux to the releases tag