Closes #102

LGTM given by: @jornvandebeek

Squashed commit of the following:

commit 766ce8fd953c3f848a45c88db13cf5790d119fee
Author: Marten Veldthuis <marten@veldthuis.com>
Date:   Tue Oct 14 15:26:23 2014 +0200

    No need to pass along parameters, these are now ivars

commit e0e312bf5e9a4825548c169887249ba845ae92d0
Author: Marten Veldthuis <marten@veldthuis.com>
Date:   Tue Oct 14 15:25:35 2014 +0200

    Give methods better names

commit 983cae78fc248e7818396032b5efba7cf79bc73a
Author: Marten Veldthuis <marten@veldthuis.com>
Date:   Tue Oct 14 15:23:09 2014 +0200

    Defaults can now be given for textvars

commit 88b26acb9bb0408d6b1b797f890e3b1f371d7df4
Author: Marten Veldthuis <marten@veldthuis.com>
Date:   Tue Oct 14 15:21:05 2014 +0200

    Extract BuildAnswer service

commit 9bf2e7d7d8f492988e15607909ea254f6f3b5ca9
Author: Marten Veldthuis <marten@veldthuis.com>
Date:   Tue Oct 14 14:39:07 2014 +0200

    Copy default textvars when creating new answer

commit ed5539c68cdb6d61d0b13dc3447a15435fdec98d
Author: Marten Veldthuis <marten@veldthuis.com>
Date:   Tue Oct 14 14:15:58 2014 +0200

    Autoprefix textvars

commit 9a7b5cfa1cc7dbe4b4efd4634c560bae057c2dd7
Author: Marten Veldthuis <marten@veldthuis.com>
Date:   Tue Oct 14 13:34:25 2014 +0200

    Require that textvars refer to defined textvars

commit 06497e051771ecd0b27c3313f40939f602e4c329
Author: Marten Veldthuis <marten@veldthuis.com>
Date:   Tue Oct 14 11:08:56 2014 +0200

    Clean up initialization of textvars

commit 32583adc849b289757520b28648cfda1bc3a1ca3
Author: Marten Veldthuis <marten@veldthuis.com>
Date:   Mon Oct 13 18:57:13 2014 +0200

    Convert textvars to react

commit bf348b981fe41d6097428d56e6fea4a00225a4ca
Author: Marten Veldthuis <marten@veldthuis.com>
Date:   Mon Oct 13 17:28:13 2014 +0200

    Fix line length

commit 6bde3c9b32574276ff3fe2461ddc24e8b3f2c546
Author: Marten Veldthuis <marten@veldthuis.com>
Date:   Mon Oct 13 16:37:53 2014 +0200

    Walking skeleton