Update the installation instructions and makefile

Makefile

@@ -10,7 +10,7 @@ ${GOPATH}/src/gopkg.in/bblfsh/client-go.v2:
 	make dependencies
 
 .ONESHELL:
-${GOPATH}/bin/hercules:
+${GOPATH}/bin/hercules: *.go cmd/hercules/*.go rbtree/*.go stdout/*.go toposort/*.go pb/*.go
 	cd ${GOPATH}/src/gopkg.in/src-d/hercules.v3
 	go get -ldflags "-X gopkg.in/src-d/hercules.v3.GIT_HASH=$$(git rev-parse HEAD)" gopkg.in/src-d/hercules.v3/cmd/hercules
 	${GOPATH}/bin/hercules -version

README.md

@@ -35,11 +35,13 @@ There is a [presentation](http://vmarkovtsev.github.io/techtalks-2017-moscow-lig
 ### Installation
 You are going to need Go (>= v1.8) and Python 2 or 3.
 ```
-go get gopkg.in/src-d/hercules.v2/cmd/hercules
-pip install -r requirements.txt
-wget https://github.com/src-d/hercules/raw/master/labours.py
+go get gopkg.in/src-d/hercules.v3/cmd/hercules
+cd $GOPATH/src/gopkg.in/hercules.v3/cmd/hercules
+make
 ```
 
+The first command is going to fail - this is intended.
+
 #### Windows
 Numpy and SciPy are requirements. Install the correct version by downloading the wheel from http://www.lfd.uci.edu/~gohlke/pythonlibs/#scipy.