Burn version information into shipped sources

When we produce a release from our repo, this triggers the toolchain to "burn"
the version information into the source code, avoiding any runtime logic.

Signed-off-by: Daniel Pittman <daniel@rimspace.net>
Improve JRuby detection handling, and error reporting

Signed-off-by: Daniel Pittman <daniel@rimspace.net>
Don't ask bundler to retry downloads

Turns out we don't have broad access to the `--retry` flag to bundler, which
is only available in very recent versions.  Theoretically we don't need it
anyway, so removing it is the short path.

Since that exposes us to some hassles caused by unreliable mirrors upstream,
we manually implement the retrying, and hope that fixes things.

Signed-off-by: Daniel Pittman <daniel@rimspace.net>