rename Bar component to StackedBar component
allow custom options for parts of multicollection
add InterleavedBar Component, convert conversion graph to use it
factor out conversion collection, change period from week to month
show normalised values in conversion graph
conversion graph callout arrows point to bars, not groups of bars
add colour key to conversion graph callout
update copy for conversion graph
make conversion graph headline dynamic
tweak styling of key in conversion graph callout
merge master into conversion-graph-comparison
minor cleanup
revert unintentional change
Merge pull request #92 from alphagov/conversion-graph-comparison

Conversion graph comparison