This commit adjusts the build flags to include version information in the LDFLAGS using the -X options. Additionally this makes the information recorded at build time more comprehensive. All build information can now be obtained via the `authelia build` command, and the `authelia version` command is now `authelia --version`. Lastly this adjusts the Dockerfile to utilize docker cache more effectively.
This change will ensure that if the curl command for the cleaning of Docker tags on DockerHub fails it will be reattempted up to 2 more times (total of 3) with a 10 second sleep between each attempt.
The clean tag logic itself within curl attempts to execute the http request upto 3 times so this will ensure a maximum of 9 attempts.
