removed `labels` argument placeholders for relationships
added LabelSet and basic add/remove
added `flatten` function plus a bit of PEP8
more label-based awesomeness
first stab at multiple rel_types on match (needs confirmation of syntax)
Merge branch 'master' into feature/labels
Merge branch 'master' into feature/match-multiple-types
Merge pull request #136 from nigelsmall/feature/labels

Basic label support
provided syntax for old and new variants
more label-based awesomeness
Merge pull request #137 from nigelsmall/feature/match-multiple-types

Feature: match multiple types
moved build script to top level
project restructure
big changes for httpstream integration
some test fixes
lots of test fixes
Merge branch 'master' into release/1.6.0
Merge branch 'master' into feature/httpstream
Merge branch 'master' into release/1.6.0
Merge branch 'master' into feature/httpstream