Update README.md to reflect current version.
Update README.md to reflect current version.

BUG=
R=cbracken@google.com

Review URL: https://codereview.appspot.com/201780043

QuiverDart/quiver_optional,google/quiver-dart,googlearchive/quiver_hashcode,QuiverDart/quiver_mirrors,googlearchive/quiver_hashcode,willyp564/quiver-dart,googlearchive/quiver_time,kevmoo/quiver-dart,QuiverDart/quiver_collection,googlearchive/quiver_optional,googlearchive/quiver_async,googlearchive/quiver_collection,trinarytree/quiver-dart,googlearchive/quiver_io,QuiverDart/quiver_collection,QuiverDart/quiver_cache,QuiverDart/quiver_check,googlearchive/quiver_cache,trinarytree/quiver-dart,alechenninger/quiver-dart,QuiverDart/quiver_iterables,QuiverDart/quiver_cache,jtmcdole/quiver-dart,QuiverDart/quiver_io,yjbanov/quiver_async,googlearchive/quiver_optional,QuiverDart/quiver_async,QuiverDart/quiver_hashcode,QuiverDart/quiver_hashcode,QuiverDart/quiver_time,googlearchive/quiver_time,jtmcdole/quiver-dart,QuiverDart/quiver_iterables,googlearchive/quiver_mirrors,QuiverDart/quiver_check,QuiverDart/quiver_strings,QuiverDart/quiver_async,EmmanuelOga/quiver-dart,QuiverDart/quiver_time,googlearchive/quiver_async,kevmoo/quiver-dart,QuiverDart/quiver_io,googlearchive/quiver_pattern,googlearchive/quiver_iterables,googlearchive/quiver_collection,QuiverDart/quiver_strings,QuiverDart/quiver_optional,QuiverDart/quiver_pattern,willyp564/quiver-dart,cbracken/quiver-dart,matgray/quiver_iterables,googlearchive/quiver_check,googlearchive/quiver_check,googlearchive/quiver_cache,cbracken/quiver-dart,googlearchive/quiver_pattern,googlearchive/quiver_strings,alechenninger/quiver-dart,matgray/quiver_iterables,googlearchive/quiver_iterables,QuiverDart/quiver_mirrors,EmmanuelOga/quiver-dart,QuiverDart/quiver_pattern,googlearchive/quiver_strings,yjbanov/quiver_hashcode,googlearchive/quiver_mirrors,yjbanov/quiver_async,yjbanov/quiver_hashcode,googlearchive/quiver_io