Add collection flag and filter to dumps
Add optional collection argument
Add test for filtration by collection
Merge branch 'master' into filter-by-collection

Conflicts:
	cmd/oplog-dump/oplogdump.go
	cmd/oplog-dump/oplogdump_test.go
Use query instead of collection
Update README for query parameter
Clarify query parameter code
Styleguide for tests: no named returns
Remove redundant test
Merge pull request #11 from Clever/filter-by-collection

Filter by collection