In order to simplify the data structures, we add back the name on the
node and instance objects. We still keep the index for, well, indexing,
but we will use the name directly from the object, in order to get rid
of the ktn/kti arguments which are passed around everywhere.

This new big patch does a couple of more cleanups in the loading of data
chapter:
  - introduce a Types module that holds most types (except the base
    Node/Instance/etc.) so that multiple other modules can use these
    (instead of only Cluster and its users)
  - bring IAlloc.hs in line with the recent changes of providing data
    types and not strings
  - removal of obsolete Utils.hs json-related functions

This makes hail compile and get a request parsed via IAlloc, but nothing
more.

This big patch converts from our home-grown monad-like constructs
(the Either stuff) to a real, Either-like-but-another-name monad.

We introduce a “Result a” monad, and this allows dropping many of the
extra constructs. Hopefully the code is also more clear.

Many of the functions could now be written in a generic-monad style,
instead of Result specifically, but that will come in future patches.

IAlloc.hs also has some unrelated patches.

Adding a small request type data structure.

We know have a working parseData function that returns the node and
instance data. This uncovered bad support for non-drbd instances ☹️

This patch moves the generic/reusable JSON functions to Utils.hs, so
that they're shared between RAPI/IAlloc.

This will be used in two ways:
  - format the response to Ganeti (easy, implemented)
  - parse the input data and build the node/instance lists (hard :)

For Ganeti 1.2 which doesn't have the ‘disk_usage’ instance query field,
we need to manually include the DRBD overhead (per disk). This patch
modifies the RAPI collection to do this, but loading from disk does not
as it's unknown if the query came from hscan or RAPI 1.2 or RAPI 2.0...

This patch modifies Rapi, the Cluster.loadData and hscan serialization to load
and save the instance run status. At instance level, we add both a boolean
field denoting the true/false run status, and a string field which holds the
original value (since we don't have a 1-to-1 mapping) for use in hscan
serialization.

The run status is not yet used.

This patch adds a new n_mem field to the node objects, and implements
read/save/show support for it. The field is not currently used (except
in the node list) but will be used for checking data consistency and
instance up/down status.

The modules are moved from the ‘top’ namespace to ‘Ganeti.HTools’, in
compliance with standard practices.

This patch moves a function to Utils and changes hn1 to be able to take
data from RAPI.

This patch changes the tryRapi function so that if the http request
succeeded, we don't try https too.

... hopefully this is more clear.

The patch adds compatibility with RAPI v1, and this required some new
JSON functions as valFromObj doesn't behave nicely.

Some other unrelated changes were done too.

This patch changes the RAPI endpoint return the same data format as the
input files. This will allow using it instead of the files.