Fixed #108: Update check should not run on dreditor.org itself.

Temporary workaround for #129.
Rewrote README.md + CONTRIBUTING.md to reflect recent changes.

Vastly simplifies and greatly enhances them at the same time.
Merge pull request #137 from sun/updatecheck-skip-dreditororg

Fixed #108: Update check should not run on dreditor.org itself.
Merge pull request #138 from sun/docs-rewrite

Rewrote README.md + CONTRIBUTING.md to reflect recent changes.
Fixed commit message feature after d.o D7 upgrade.

1. An adjusted issue title is no longer taken over as commit message.
2. The commit message is no longer prefixed with Added|Fixed depending on issue category.
Merge pull request #141 from sun/commit-message-d7

Fixed commit message feature after d.o D7 upgrade.
Merge branch '1.x' into sun