Improved test ValueSnakStoreTest->testStoreSnak

Change-Id: I531c314b607201e6ae1518f343790f53bd379262
Added internal snak type restriction to ValuelessSnakStore

Change-Id: Ic4b41aeef3901a2ae62941648e125f32f7394e56
optimized imports

Change-Id: I04ae2fe5dae8d26df32bd4da3cef88d05637cfc2
Added ClaimRow data structure

Change-Id: Ie139a6d2074c3aedea865f7faa8baf2bfd0e7c37
Added base for ClaimsTable

Change-Id: I2115aca3652a6b54084dbf7a7673b9f419e6ecc9
Implented ClaimsTable->insertClaimRow

Change-Id: I9939916026147d18c5d8e3b8ff758f984ac6dbcb