add new checksum type to system
document new checksum type and update to new Guava
add endian-reverser wrapper for checksum algorithms

can be removed once a SQL upgrade script fixes
old hashes in the database
change Adler-32 and CRC-32 to use Guava implementations
add new checksum type to enumeration, corresponding with model
clarify checksum provider API behavior
create new file-size trivial checksum provider
make new file size checksum algorithm available for retrieval
remove old non-Guava hash function wrapper classes
rename "integration" test to better match its nature
add new checksum type to schema
remove unused import
add SQL for querying and inserting checksum algorithms
ensure on start-up that the new checksum algorithm is in the DB
add copyright headers
adjust results parameter in flaky testInputs integration test

cc: @joshmoore, @bpindelski
add some javadoc
merge dev_5_0 -D org: PR 2242 (Use mklink under Windows)
merge dev_5_0 -D org: PR 2595 (12311 auto memory)
merge dev_5_0 -D org: PR 2596 (Groups users menu 12082)