update to Sceptre 2

[bilardi]

• added tag v0.1.2 for status of the package compatible with sceptre version from 1.3.4 to 1.5.0 (I've tested versions 1.3.4 and 1.5.0)
• updated Makefile, README.md, requirements.txt, configuration files, hook and resolver to Sceptre 2
• updated AUTHORS.md and CHANGELOG.md
• added tag v1.0.0 for status of the package compatible with sceptre version >= 2.1.2 (I've tested versions 2.0.0, 2.0.1, 2.0.2, 2.1.0, 2.1.2, 2.1.3, 2.2.0 and 2.3.0)

PS: the versions < 2.1.2 have the error: AttributeError: 'Stack' object has no attribute 'connection_manager'

[jaymecd]

appreciated @bilardi, I will take a closed look in upcoming days.