Add seeds.txt file from sipas DNS dumps

File downloaded from http://bitcoin.sipa.be/seeds.txt
See Google Code Issue #457
SeedPeers gets peer info from seeds.txt resource

* Modify SeedPeers to read entire resource in to array.
* Remove dependencies on old implementation from unit tests.

See Google Code Issue #457
Merge branch 'master' into msgilligan-issue457
Remove @author tags
First cut at Gradle script to build addrs.txt
Move 30MB seeds.txt out of core and into contrib
Remove seeds.txt (it's too big for git, I think)
SeedPeers reads from smaller addr files for 3 nets

 * Text files for production, test, and unit test
 * Files have IP addresses only
 * 600, 25, and 1 address each respectively
 * Improved implementation and unit tests
Placeholder not needed anymore
copyToCore task to copy to 'core' module resource

Also, change download dir for sipas seeds.txt to builder
Merge branch 'master' into msgilligan-issue457
Last 2 changes to prepare Pull Request:

1) Use a global public static variable on the SeedPeers class that holds an InputStream.
2) Remove filtering of ipv6 addresses (both in the Gradle script and in SeedPeers)
Remove Gradle wrapper files, update comments
merge remove of Gradle wrapper