Support for PEM Passphrase

[stevendore]

I was helping a client set up Hitch and their .pem file was passphrase protected. This caused an issue with starting Hitch,

... systemd[1]: Starting hitch…
... hitch[40030]: Trying to initialize SSl contexts with your certificates.
... hitch[40030]: Enter PEM pass phrase:
... hitch[40030]: {core} PEM_read_bio_PrivateKey: error: 096406D: PEM routines: PEM_def_callba...ssword
... Systemd[1]: hitch.service control process exited, code=exited status=1
... Systemd[1]:failed to start hitch.
... Systemd[1]: Unit hitch.service failed.

A picture of the output can be seen here.

After speaking with @daghf he concluded PEM passphrase was not supported but offered a solution to remove the passphrase as long as the pem file contained the passphrase bit.

openssl rsa -in [file1.key] -out [file2.key]

Is it possible to add PEM passphrase to Hitch or to better communicate this in the docs?

I did notice it mentioned here but nothing came of the PR.