Changes for v3

[tptee]

• Expose almost all of the API as public. This allows consumers to hook into the history cycle using the newly exported action types (LOCATION_CHANGED, REPLACE, etc).
• Handle history's state field for location-specific state.
• The action creators now take the same arguments as their equivalent history functions (either a pathname string or a full location descriptor object).
• <Link> now has an optional replaceState prop. When true, <Link> will dispatch a replace action instead of a push.
• Removed the unused historyAction field. This is a breaking change.

[coveralls]

Coverage increased (+0.05%) to 97.015% when pulling 5259ecc on feature/tres-leches into 40228bf on master.

[divmain]