Fix missing options bug in GetClaims

The problem is that the raw mode setting is false when the builder
is constructed. Using lazy initialization to create the serialization
options seems to work.

(This also fixes GetClaimsTest, which misfired on snak's datatypes
now correctly being included in the output.)

Change-Id: Ieb1dfec050a2963eab675fd831f8da8bede17db3
Add tests for api xml format

Tests for wbgetclaims and wbgetentities xml format

Change-Id: Icb29307d44c79059e59c7e0fc275d2abb5fc0ecd
Merge "Fix missing options bug in GetClaims" into mw1.24-wmf19
Merge "Add tests for api xml format" into mw1.24-wmf19