SERVER-13561 Improve wire API message validation
SERVER-13579 Wait for deletion after migration in feature2.js
SERVER-13498 Get rid of LockStatus

This change removes all usages of LockStatus and pushes the lock
acquisitions to be inside the respective commands. This is a
refactoring on the way to per-document locking.
SERVER-13600 Forbid implicit construction of NamespaceString from StringData.
SERVER-13600 Remove string-copying implicit conversion operator from NamespaceString to std::string.

By replacing the implicit conversion operator from const
NamespaceString&->std::string with one from const NamespaceString&->const
std::string&, we at least eliminate an implicit copy.  Better might be to get
rid of the implicit conversion entirely, but we might want to start by removing
APIs that take std::string when they mean NamespaceString.