[RocksDB] fix prefix_test

Summary: user comparator needs to work if either input is prefix only.

Test Plan: ./prefix_test --write_buffer_size=100000 --total_prefixes=10000 --items_per_prefix=10

Reviewers: dhruba, igor

Reviewed By: igor

CC: leveldb

Differential Revision: https://reviews.facebook.net/D14241
Fix a memory leak happened in table_test
Update the installation guide for mac users.
Add more guide for mac users.
Fix the format in INSTALL.md
Add TableOptions for BlockBasedTableFactory

We are having more and more options to specify for this table so it makes sense to have a TableOptions for future extension.
Allow users to profile a query and see bottleneck of the query

Summary:
Provide a framework to profile a query in detail to figure out latency bottleneck. Currently, in Get(), Put() and iterators, 2-3 simple timing is used. We can easily add more profile counters to the framework later.

Test Plan: Enable this profiling in seveal existing tests.

Reviewers: haobo, dhruba, kailiu, emayanke, vamsi, igor

CC: leveldb

Differential Revision: https://reviews.facebook.net/D14001
Revert "Allow users to profile a query and see bottleneck of the query"

This reverts commit 3d8ac31d7168c916d6f2f0729eb627b07d8f082b.
Improve the readability of the TableProperties::ToString()