Updated the shell script that generates the certificates and the
documentation accordingly.
Caveat: now installation is a 2-step procedure, installing OS and
application are split into 2 commands.

Don't lock the allocator with spin.

Mentions webauthn.io at the end of install.md.

Fixes #25

Update the ring dev dependency version.

Don't dereference slices obtained from include_bytes.

Fix run_desktop_tests.sh script

Pass features to crypto bench example.

The script begins with `set -eux` and therefore will fail when using an
undefined variable. This is the case with `TRAVIS_OS_NAME` outside of
Travis.

Enable Travis on OSX

Only do the build/link check. The unit tests are only ran on linux.

Decrease the number of tests in debug mode, to account for slower CI on Travis

Change the way private key and cert are embedded.

Python3 on Travis is old (3.5) so crcmod is installed by pip anyway.

Python3-setuptools seems old and installing crcmod (dependency from
tockloader) from pip fails because of this. Installing from the system
package manager should solve the problem.

Update install.md

Fixed the link for TC2050 Tag-Connect programming cable. The right cable that connect to the Tag-Connect TC2050 ARM2010 adapter is the TC2050-IDC-NL instead of TC2050-IDC-NL-050-ALL.

Trusty is quite old and Xenial is the default. We should be fine not
giving any distribution. This will give us a more recent OpenSSL
version.

OpenSSL seems to serialize bigints as signed value, which means the ECC
key may end up being 33 bytes instead of the 32 bytes we're expecting,
causing build to fail.
The shell script extraction is now replaced by a build.rs script that
uses OpenSSL to extract the content and do sanity checks.
Forcing generating cryptographic materials now always generate a key and
a certificate (useful to compile/flash multiple keys without them being
considered as clones). The self-signed CA is left untouched.

Bump rust-toolchain and linked-list-allocator versions.

Update arrayref version in libraries/crypto.