Allow wildcard at end of deref_expr.

Fixes issue #39.
Failing tests for qualified wildcards.
Fix compilation of qualified wildcards.
Update constructors in test.
Add a test for deeply-nested select *.
Check for required Java version when starting sbt.
Merge pull request #98 from sellout/minor-fixes

Check for required Java version when starting sbt.
Merge branch 'master' of github.com:slamdata/slamengine into graphviz
Add a note to the Readme that building requires Java 7.
pull ExprOp out of pipeline.scala

Conflicts:
	src/main/scala/slamdata/engine/physical/mongodb/pipeline.scala
break out all merging-related code to merge.scala
(not including the merge() methods, yet)
pull out all merging-related code to merge.scala
Merge pull request #99 from sellout/minor-fixes

Add a note to the Readme that building requires Java 7.
Merge pull request #93 from sellout/39-qualified-wildcard-2

Compile qualified wildcards.
Merge pull request #100 from mossprescott/refactor-pipeline-2

#51: pulled out all merging-related code to merge.scala
add missing tests; fix Like in planner
Merge pull request #101 from mossprescott/fix-like

add missing tests; fix Like in planner
Merge branch 'master' of github.com:slamdata/slamengine into graphviz