Imports of package metrics

PathSynopsis
encoding/jsonPackage json implements encoding and decoding of JSON as defined in RFC 7159.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
github.com/rcrowley/go-metricsGo port of Coda Hale's Metrics library
slicesPackage slices defines various functions useful with slices of any type.
stringsPackage strings implements simple functions to manipulate UTF-8 encoded strings.
syncPackage sync provides basic synchronization primitives such as mutual exclusion locks.
sync/atomicPackage atomic provides low-level atomic memory primitives useful for implementing synchronization algorithms.
timePackage time provides functionality for measuring and displaying time.