fix(reducer): allow setting paths ending in numbers

[levithomason]

Fixes #228, tests added

_.set does not respect numeric object keys. Use _.setWith instead:

const path = getDotStrPath('/analyses/123')  // => 'analyses.123'

_.set(path, { data: true }, {})              // => { analyses: [ undefined x 123 ] }

_.setWith(Object, path, { data: true }, {})  // => { analyses: { 123: { data: true } } }

There are many lodash issues and SO posts about this bizarre design decision but it looks like it is not likely to be changed.