Make PromDash deal with empty metric names.

The Prometheus server is being changed to drop metric names after
transformations like sum(), avg(), etc., since the result of these
transformations is not the original metric anymore. Thus, the metric
name of timeseries may be empty now. PromDash needs to deal with this.
Merge pull request #214 from prometheus/julius/empty-metric-name

Make PromDash deal with empty metric names.
Remove dependence on "instance" Metric label.
Support UTF-8 for encoding/decoding widget links.
Add link to prometheus version of expression.
Merge pull request #217 from prometheus/jump-to-prometheus

Add link to prometheus version of expression.
Merge pull request #215 from prometheus/pie-chart-instance-fix

Remove dependence on "instance" Metric label.
Merge pull request #216 from prometheus/peter-being-difficult

Support UTF-8 for encoding/decoding widget links.
Upgrade to angular 1.3, revert to using CDN for angular, jquery,
jquery-ui.
angular/jquery for specs
Merge pull request #218 from prometheus/re-cdn

Upgrade to angular 1.3, revert to using CDN for angular, jquery, jquery-ui
link to prometheus functionality for pie charts
Merge branch 'master' of github.com:prometheus/promdash
Add periods to end of encode/decode comments.
Merge branch 'master' into annotations
wip