Merge pull request #1 from elasticsales/segment_literal_notation

Support segment-literal notation '[' for referencing properties that are not valid identifiers.
Merge remote-tracking branch 'origin/fix-invalid-templates'

Conflicts:
	pybars/_compiler.py
Don't raise AttributeError in resolve()
Merge branch 'master' of https://github.com/elasticsales/pybars into elasticscales-master

Conflicts:
	pybars/_compiler.py