Create new API POST/GET `/metrics`

[ericpassmore]

POST pushed JSON with

• start_block
• end block
• config slice id
• elapsed time

GET by default provides

• number of jobs
• average time
• stddev on average
• medium time
• 25%, 75%, 90% times
• longest running job time

GET with list=all param shows list of all jobs with

• start_block
• end block
• config slice id
• elapsed time