Some work on the dependencies page

- renamed .markdown files to .md
- a fix in the about page
- a new (still empty) API page

dependencies.md

@@ -0,0 +1,29 @@
+---
+layout: page
+title:  "Dependencies"
+permalink: "/dependencies"
+order: 100
+categories: dependencies
+---
+
+`jabit-core` contains the Bitmessage context and all entities that will be used by the other modules.
+Whatever you do, you'll need this.
+
+`jabit-networking` manages connections to the Bitmessage network. This is probably the most complicated
+part of the Jabit project. TODO
+
+`jabit-repositories` is where the entities from core are stored. The default implementation uses JDBC
+to access a H2 database. It should mostly be easy to use other SQL databases (I'll happily accept pull
+requests) but if you want to use some NoSQL database or a very restricted one (as with SQLite) you might
+want to create your own implementation.
+
+`jabit-cryptography-bouncy` impmlements everything related to encryption, cryptographic hashes and
+secure random numbers. As the name suggests, it uses the [Bouncycastle](https://www.bouncycastle.org/)
+library.
+
+`jabit-cryptography-spongy` is basically a copy of the spongy one, but using
+[Spongycastle](https://rtyley.github.io/spongycastle/) instead.
+
+`jabit-wif` lets you import from and export to the Wallet Import Format, which is used by PyBitmessage to store its identities.
+
+`jabit-extensions` you won't usually need, it contains a few helper classes for if you want to build protocol extensions.