Capture warnings in JSON/report

[rsuchecki]

Some warnings, generated e.g. during tool version validation
WARN: Declared tool version string 0.7.17-r1188 not found in container image spec rsuchecki/bwa:0.7.17_8b61e2a77c105f3ec28d260b556af5cf12c49111
are printed to the terminal but should probably make their way into the report (via runmeta.json)

repset/lib/Validators.groovy

Line 52 in cec08e2

log.warn "Declared tool version string ${rec.version} not found in container image spec ${rec.container}."

possibly also

repset/main.nf

Line 70 in cec08e2

log.warn "Malformed real reads entry will be ignored: ${it}"