Add endpoint for fetching dataframes needed for history matching

[ManInFez]

In order to prevent transferring more than needed, ert-storage should offer data required for performing history matching.

Given a response vector V and D which have observations at V[1] and V[3] and D[4], it result in a dataframe like:

   rel. 0, rel. 1 ...
V1 [ 0.5,   0.6,  ... ] 
V3 [ 1.3,   1.6,  ... ] 
D4 [ 3.5,   4.6,  ... ] 
.. [ ... ,  ...,  ... ]   

parameters should result in a dataframe like:

   rel. 0, rel. 1 ...
P1 [ 0.5,   0.6,  ... ] 
P2 [ 1.3,   1.6,  ... ] 
P3 [ 3.5,   4.6,  ... ] 
.. [ ... ,  ...,  ... ]   

The endpoint should support queries, i.e. give me responses for these particular observations.