[DO NOT MERGE] 543 home page ui tweaks

[DO NOT MERGE] hey @pld, i would appreciate feedback on the approach I used to make the ajax requests
as below, no need to append `xhr` to append the `query` query parameter you will need to modify the `get-url` function to accept a parameters argument, this is how `post-url` works so you can use that as a guide, https://github.com/onaio/zebra/blob/master/src/cljs/ona/api/io.cljs#L25, you'll also need to modify/add a test to here, https://github.com/onaio/zebra/blob/master/test/cljs/ona/api/io_test.cljs