Support for Intel PMEM

[hesuyouren]

What changes were proposed in this pull request?

1. Memkind was used for pmem setting
2. Pmem storage is now available
3. New data structure - SHARED_LOG is available.

How was this patch tested?

Tests are added in corresponding test directories.

Please review https://ucbrise.github.io/jiffy/contributing/ before opening a pull request.

[anuragkh]

@hesuyouren I have a lot of comments, but the two high level ones are:

• You've checked in all the python .egg files in this PR -- could you please remove them first?
• All the test files with PMEM have your specific PMEM path hardcoded; we probably want to keep that generic. Also these tests should be optional, and the default mode should be to test with regular memory (we should have both forms of tests).