Fix all of our pom.xml versions to be 2.1-SNAPSHOT

I meant to keep reusing the 2.1 version number for the entire
2.1 series during development, but botched it during the 2.1.4
development cycle and set it to 2.1.4-SNAPSHOT by mistake.  Put
it back to 2.1-SNAPSHOT since 2.1.4 is released.

Change-Id: I37e206c0609bf3fd94a5aab8ea301c98b7fb013e
Signed-off-by: Shawn O. Pearce <sop@google.com>
17 files changed