Correct appearance issues with Settings popover.

* Height of popover now matches the height of the content in the view
* Explicitly nil accessory views when not used, fixing an error where unexpected accessory views would appear.
[Fix #165] Add caption headings to the picker.
[Bug #164] Disable autocorrect on sensor fields in the Settings popover.
[Bug #164]: Modify next/return button handling while adding a sensor in the Settings popover.

* Address field displays the "URL" keyboard
* "Next" button appears while editing the name field (moves selection to address field)
* "Done" button appears while editing address field (dismisses keyboard)
[Bug #164] Keyboard still visible when pickers in biographical information view are visible.

Note that this animation is somewhat jarring, but a future direction should be to completely remove theses pickers (see bug #112).
[Bug #164] Don't require a name when adding a sensor via the Settings popover.
Swap address field and text field, to be more in line with the device walkthrough and the fact that a name is not required since 3bce5a7e5bdd3ae1bf5be0d5ea8c52b7b1e5775c.
[Bug #164] Make "next" and "done" buttons do something during device setup walkthrough.

Remove some old code to make the keyboard disappear if you tap outside the table.
Move header files into the appropriate directory structure.
[Bug #164] Fix "next" and "done" handling with height/weight field (regression from touch logging).
Expose the current operation of a BWSDeviceLink.
Fix bug where status of device link would reset to NULL during chained sequences

Bug #148 could help with this.
Add convenience method to check if a DeviceLink has been initialized without calling /initialize.
[Bug #163] Rough-in for "pending operations" screen.

Operations can be canceled with the Edit button or swipe-to-delete.
[Fix #163] Add option to cancel captures when capture card dismissed.
Missing const.
[Fix #112] Implement custom PickerActionSheet.

Needs polish (what doesn't in wsabi?) but allows you to use landscape orientation.
[Fix #167] Remove tap outside modal to dismiss functionality.

Adds system "Cancel" button to right, where possible.
[Fix #169] Save/restore last selected person.
Resize images for thumbnails more naïvely.

* Draws thumbnails true to their aspect ratio and also fixes an issue where the indexed bitmap image returned from the fulcrum scanner could not be scaled down.
* Remove now unused third-party scaling code.

In the future, it might be a good idea to look into just doing a good-old matrix scaling transformation (CIImage iOS 5 and later), but we would need to beef up our image format handling (no indexed bitmap support natively, for instance).