Add coveragerc and update Makefile

.coveragerc

@@ -0,0 +1,6 @@
+[run]
+branch = True
+source = camelot
+include = */camelot/*
+omit = 
+    */setup.py

Makefile

@@ -1,6 +1,15 @@
 PYTHON ?= python
 NOSETESTS ?= nosetests
 
+help:
+    @echo "Please use \`make <target>' where <target> is one of"
+    @echo "  clean"
+    @echo "  dev            to install in develop mode"
+    @echo "  undev          to uninstall develop mode"
+    @echo "  install        to install for all users"
+    @echo "  test           to run tests"
+    @echo "  test-coverage  to run tests with coverage report"
+
 clean:
     $(PYTHON) setup.py clean
     rm -rf dist