Bring back requirements

requirements.txt

+tabulate
+click>=7.0
+PyYAML>=3.12
+iminuit>=1.3.3
+jupyter>=1.0.0
+ipython>=6.2.1
+matplotlib>=2.1.2
+numpy>=1.14.1
+pandas>=0.22.0
+scikit-learn>=0.18.2
+scipy>=1.0.0
+scipy-extra>=0.1
+seaborn>=0.8
+uncertainties>=3.0.1
+more-itertools>=6.0.0
+gitpython
+luigi>=2.7.6
+b2luigi>=0.4.4
+probfit>=1.1.0
+pyPDF2>=1.26.0
+recordclass>=0.13.2
+git+git://github.com/FelixMetzner/TemplateFitter.git
+git+ssh://git@gitlab.ekp.kit.edu/fmetzner/AnalysisTools.git
+git+ssh://git@gitlab.ekp.kit.edu/mapr/eFFORT.git