update ssl_file to pass on the full path

See merge request !2

The ssl_file directive must be passed as a full path onto the
openssl_probe library which reads it from the SSL_CERT_FILE env var.

add an i686 musl build

See merge request !1

Due to 12412f47 we need to avoid bumping
to development version numbers.

Ensure that releases have signed commits

The download URL didn't work out as I had hoped. Fix it for now until
there's a better way.

This reverts commit b8c685af. cargo-rpm
is unable to handle versions like this. Upstream issue:
https://github.com/iqlusion-io/crates/issues/38

When the yum repo config wasn't pinned to 7.2 it was upgrading the
packages from the latest version which caused the latest OpenSSL to get
pulled in from a newer CentOS. CentOS 7.2 used an older version. This is
important because the newer OpenSSL is not included in XenServer 7.x.

GitLab keeps the artifacts from each job in its own zip so this job will
bring them all together into one.

openssl-probe fixes the musl based binary to be able to find OpenSSL's
CA's so that musl can include a static copy of OpenSSL.

build -> test
release -> build

build was a bit confusing since it was really just compile testing and
doing a format check of the code base while release was building the
binaries to publish.

This RPM should work for CentOS 7.2 machines and XenServer 7.x machines.

Add a CentOS 7.2 based build environment for generating RPMs.

Make it more clear as to what we are targeting

This will allow a package to be built up using cargo rpm build.

Upgraded from Rust 1.26.0 (rustfmt 0.4.1-stable) to Rust 1.26.1 (rustfmt
0.4.2-stable) and this was the change

Most other LDAP utilities appear to use 'bindpw' so rename to that for
consistency with other tools.

Added pronounciation hint. Fixed config file format. Added more links to
OpenSSH docs.

Use structopt to parse the command line allowing the configuration file
to be specified as well as giving more helpful output back to the user
over what went wrong with their invocation.

To hopefully avoid users exposing their bind passwords, require that the
config file have 0400 as its permissions.

The goal is to be as simple as possible to provide something secure so
add a basic README that hopefully covers things.

More natural default

This directly affects what is expected in the config file and it feels
more natural to be lower case.

Add additional information to the error messages to make them more
descriptive while using the older style of a main function to be able to
use the Display form of errors instead of the Debug.

Simplify the name. We'll pronounce it sackle like handle.

Roughly this will talk to a LDAP server and grab the public SSH key from
an attribute and print it to stdout so that OpenSSH can use it. The
config file will need to be read from a more permanent location and
error messages need to be improved.