Form: allow browser-info collection to be configurable

[jayaddison]

Describe the reason for these changes and the problem that they solve

As described in #21, some use cases (such as RecipeRadar) do not require all of the browser information fields that are currently retrieved by default. We can make the selection of relevant fields configurable as an option to the Feedback API.

Briefly summarize the changes

1. Add a browserInfo constructor argument to the Form page -- with a default of all existing browser environment properties already collected.
2. Only gather browser information for properties that have a truthy value in the Form instance's browserInfo properties.
3. Allow consumers of the Feedback component to specify options.browserInfo to configure their preferred set of browser info fields to collect.

How have the changes been tested?

1. Local development testing.

List any issues that this change relates to
Resolves #21.