Adding support for labels using unsigned intergers

Added

• Support for labels using unsigned integers.

v1.0.0

Added

• Support for empty buckets tag, which will generate nil buckets for the prometheus Histogram and use default prometheus buckets.
• Support for empty objectives tag, which will generate nil objectives for the prometheus Summary and use an empty objectives map after all.

Changed

• Breaking: prometheus.Histogram is now used to build histograms, instead of prometheus.Observer, which means that previous code building prometheus.Observer won't compile anymore.

Removed

• Breaking: default buckets on histograms. All histogram should explicitly specify their buckets now or they will fail to build.
• Breaking: default objectives on summaries. All summaries should explicitly specify their objectives now or they will fail to build.

Fixed

• Summary building was not failing with malformed objectives.

Migration instructions

If you're migrating from a v0.x.y, you will need to:

• Replace Metric func() prometheus.Observer by Metric func() prometheus.Histogram
• On prometheus.Histogram metrics, add buckets:"" which will use the prometheus.DefBuckets bucekts, or even better, define yours.
• On prometheus.Summary metrics, add objectives:".5,.95,.99" to keep using the same objectives, or define yours.

Prepare release v0.3.0 for summary changes (#25)

• Add objectives to summaries through struct tag and set default values when none specified
• Upgraded client_golang to v1

v0.2.1

Changed
Reduced the number of default buckets from 12 to 7 between 0.05s and 10s

Included the implementation builder for summaries

v0.2.0

Updated CHANGELOG for v0.2.0 release

Bugfix: Not failing when embedded labels are wrong

• Not failing when embedded labels are wrong #13

Initial release

v0.1.0

Initial release