Ignore build files

Also attempts to account for other common activities like
install_local_hadoop, sqstart, and SQL regression tests.

Hidden files can be shown via git ls-files -v (or --other).

Remove sql.error_event.template from versioning, since it is generated
by the build.

Change-Id: I6b778f3ba4b945cf0b7b41f70173659065246b79
Merge "Ignore build files"