export keys: html.
export keys: working implementation.

Code is based on `signing.js` and is incomplete (cannot select which
keys to export).

Upon successful password entry, the keys are displayed in

<address>,<secret exponent>

form in the "tools" output box in the middle of the screen, one key per
line. Main hierarchy keys in the extension store are exported, including
"pocket" ones, but Stealth keys are not.
export keys: test unit skeleton (copied from `signingSpec.js`)
export keys: don't ask user what to export; change icon.

User input validation seems to be tricky.
export keys: remove unused dependencies `bitcoinjs-lib` and `util/stealth`.

This may be undesired: former can (probably) be used to change the
export format, latter can (perhaps) be used to export master sectet and
known keys with history.
Move the buttons to create new pockets to the header for the section.
Make the new pocket form more clear and more like the multisig one.
Change button aspect when in form.
add Contacts.searchKeys function to search for key with a certain attribute.
Avoid adding contacts with the same keys twice. Fixes #172.
Show unconfirmed balance for the pocketoverview more clearly, also show the 'confirmed' balance, instead of 'current', since we're showing confirmed in other parts as well.
Process pocket addresses normally within their own pocket. Allow special treatment so we can query their balances but normally don't show unless they have balance.
Fix unit test for latest changes in the pockets spec.
Fix more tests for pocket spec change.
Remove now uneeded branches.
fix some comments.
Fix call to max.
Fix wrong call to selectAll.
Make the wallet properly check for dust per output and avoid generating dust outputs.
Also update dust threshold.
Some more notes for hacking the css.