Upgrade to spark-0.9.0.

Because this version of spark is available from maven-central, we can make optiq-spark part of the regular build, and remove the spark profile.
Fix https://github.com/julianhyde/optiq/issues/53, "Allow WHEN clause in simple CASE expression to have multiple values".
Fix https://github.com/julianhyde/optiq/issues/141, "Downgrade to guava-11.0.2".

This is necessary for Hadoop compatibility. Later versions of Guava can also be used.
Remove duplicate maven-source-plugin.
Fix https://github.com/julianhyde/optiq/issues/145, "Unexpected upper-casing of keywords when using java lexer".
Fix https://github.com/julianhyde/optiq/issues/128, "Support WITH queries (common table expressions)".

Add generics to SQL parser.
Code formatting: Convert all enum constants to upper-case.
Fix https://github.com/julianhyde/optiq/issues/148, "Less verbose description of collation". Also, optimize RelTraitSet creation and amortize RelTraitSet.toString().
Fix https://github.com/julianhyde/optiq/issues/147, "Create a new kind of SqlCall that keeps operands in fields, not an operands array".
Convert some more SQL parse tree nodes to have named, typed fields.
Support Windows-style file separator, otherwise build fails at Windows due to suppressions not used
Fix https://github.com/julianhyde/optiq/issues/158, "Optiq fails when call Planner.transform() multiple times, each with different ruleset".
Fix ONE_MINUS_EPSILON.
Fix https://github.com/julianhyde/optiq/issues/160, "Allow comments in schema definitions".
Add SqlOrderBy, a sub-type of SqlCall to represent an ORDER BY clause applied to a non-SELECT query.
Fix bug in OptiqAssert.returnsUnordered.
Fix https://github.com/julianhyde/optiq/issues/156, "Optiq should recognize 'SYSTEM TABLE', 'JOIN', 'INDEX' as table types".
Fix bug deriving the type of a join-key.
Fix https://github.com/julianhyde/optiq/issues/153, "Error using MongoDB adapter: Failed to set setXIncludeAware(true)".

Added flag to use the correct XML parser; also disabled spark engine unless Spark libraries are on the class path and spark=true is specified in the connect string.

Fixed path to mongo-zips-mogel.json in HOWTO.