0.2.2

CHANGES:

• unikernel: updates to mirage 4.5 (#36 @Julow)
• unikernel: add tls-proxy parameter
• unikernel: exit with argument_error on startup errors
• unikernel: update to logs-syslog 0.4 (no console)
• initialize_fs: pretend root is around
• fix unused functor parameters
• remove mirage-random-test dependency
• use ohex instead of hex