Sort transactions by date instead of status.

List transactions by most recent date on the overview and transactions
pages. Sorting by status shows all the orphaned blocks first, which is
confusing.
Better fix for minting icon lagging the GUI.

Split updating user and network weights into a separate function. Update
them only every 30 seconds.
Fix proof-of-stake block signing.

Add back mistakenly removed SignBlock() in proof-of-stake section of
BitcoinMiner().
Merge pull request #15 from skwurp/pull-1

Critical: Fix proof-of-stake block signing.
Merge pull request #16 from skwurp/pull-2

Better fix for minting icon lagging the GUI.
Merge pull request #17 from skwurp/pull-3

Sort transactions by date instead of status.
Enabled DNS seeding by default, added 1 DNS seed
Merge pull request #19 from keremhd/master

Enabled DNS seeding by default, added 1 DNS seed
Merge remote-tracking branch 'upstream/master'