Added debian folder with rules to build .deb package

$ dpkg-buildpackage -rfakeroot

There's some bug in Ubuntu 12.04:
https://github.com/spesmilo/libbitcoin/issues/12
[debian] Removed --enable-bdb build flag

Support for bdb was removed at 0e43299b97ce75b9a8db4f65cc1ac488fc1b7637
[debian] Fix some lintian warnings

binary-control-field-duplicates-source
build-depends-on-build-essential
missing-debian-source-format
missing-field-in-dep5-copyright
out-of-date-standards-version
package-lacks-versioned-build-depends-on-debhelper
source-nmu-has-incorrect-version-number
unused-license-paragraph-in-dep5-copyright
unversioned-copyright-format-uri
using-first-person-in-description
[debian] Fixed more lintian warnings

changelog-should-mention-nmu
native-package-with-dash-version
outdated-autotools-helper-file
[debian] Added .ipp files
[debian] Rename package to libbitcoin0

Removes lintian warning: package-name-doesnt-match-sonames
Added instructions to build Debian package to README
[debian] Missing dependency and last changes in Description
[debian] Sort files
[debian] Make it clear that our AGPL3 has additional permissions
[debian] Include database folder with .hpp files
Added myself to AUTHORS
[debian] Bump version to 2.0.0
move calculate_stealth_bitfield() into public API.
Integrate the secp256k1 library
Update the documentation for the new ec_keys types
allow to select custom path for libsecp256k1 during configure.
add *temporary* ec addition function (using OpenSSL).
Remove comment-only bigint files.
Fix array initializer.