Merge pull request #32 from cashlo/master

Adding absolute(), averageAbove(), averageBelow(), and maxValue support for nonNegativeDerivative
main: forward /find and /info requests

For the sake of less confusion, forward /find and /info requests so
people can stay on one service (carbonapi) for all of their needs.
Merge pull request #33 from grobian/master

main: forward /find and /info requests
Merge pull request #34 from cashlo/master

Adding some more functions
find: use standard url
implement aliasSub function
tests for aliasSub function
add 'Known issues' section to README
Merge pull request #35 from ikruglov/master

add support of aliasSub() function