Fixes to initializable

I added some documentation, but I also think there is a bug regarding
the level super is being called at (it should be called regardless of
whether bias_initialization is True or False).

I've also set a sensible default on the class instead of by using
getattr, and changed the negative into a positive because I think it's
more transparent.
Fix
Rename Initializeable to Initializable
Introduce DaisyChain class
Removed redundant list comprehension
Rename DaisyChain to Sequence
Fixing some ambiguity.

Right now the no_bias_initialization refers to two things: Whether to
push the biases_init configuration, and also whether to accept it or
not. I think the variable should refer to only one of these two cases
(and if both cases need to be supported, they should probably be
represented by different attributes). This way I think it is much
clearer what is going on.
MLP shouldn't inherit from Initializable
Don't recycle variable
merge master
Merge branch 'master' into daisychain
init
Combined with sequence
Redundant import
Get rid of push_bias_initialization
Fix typo in docstring
Remove redundant class attribute
Seems like we want to push down biases_init even if the child class doesn't have one, in case the child of the child needs it...
__init__ for Initializable
Merge branch 'master' into initializable