Eliminate VersionSet memory leak

Summary:
ManifestDumpCommand::DoCommand was allocating a VersionSet and never
freeing it.

Test Plan: make

Reviewers: igor

Reviewed By: igor

Differential Revision: https://reviews.facebook.net/D22221
Improve Options sanitization and add MmapReadRequired() to TableFactory

Summary:
Currently, PlainTable must use mmap_reads.  When PlainTable is used but
allow_mmap_reads is not set, rocksdb will fail in flush.

This diff improve Options sanitization and add MmapReadRequired() to
TableFactory.

Test Plan:
export ROCKSDB_TESTS=PlainTableOptionsSanitizeTest
make db_test -j32
./db_test

Reviewers: sdong, ljin

Reviewed By: ljin

Subscribers: you, leveldb

Differential Revision: https://reviews.facebook.net/D21939
Add missing implementaiton of SanitizeDBOptions in simple_table_db_test.cc

Summary:
Add missing implementaiton of SanitizeDBOptions in simple_table_db_test.cc

Test Plan:
make simple_table_db_test.cc
Fix the error of c_test.c

Summary:
Fix the error of c_test.c

Test Plan:
make c_test
./c_test