Add support for Graphite web's aliasQuery() function

[carrieedwards]

This PR adds support for Graphite web's aliasQuery() function.

The aliasQuery() function is defined as:

aliasQuery(seriesList, search, replace, newName)
Performs a query to alias the metrics in seriesList.

&target=aliasQuery(channel.power.*,"channel\.power\.([0-9]+)","channel.frequency.\1", "Channel %d MHz")
The series in seriesList will be aliased by first translating the series names using the search & replace parameters, then using the last value of the resulting series to construct the alias using sprintf-style syntax.

[CLAassistant]

All committers have signed the CLA.

[npazosmendez]

I think the expected behavior is a little bit more complex. The documentation is not very clear, but this is the original issue that requested the functionality: graphite-project/graphite-web#1936

If I understand correctly, the search+replace in the metric name results in another query that should be evaluated. Then get that series to construct the printf-like string; that will be the alias for the original series.

This requires evaluating an expression and re-querying the metric store in the middle of the processing.

[npazosmendez]

Closing this for now as a more complicated approach is needed. We will track this task here #5