Revise tag view header

[xmatthewx]

Since the tag filter view can't include the Discover/Make tabs, we'll revise the initial design.

• remove extraneous details: "tags", "hashtag", "X", and the underline
• blue header contains back arrow and no text
• leave large "#chicago" in a medium gray (like avatar or "X")

[xmatthewx]

On the Android side, should we set all the strings to an empty string? Or remove the label from the manifest and remove all the string definitions?

[gvn]

I'm setting them to an empty string because it seems to need a string even if it's just empty...