Release 0.3.1

[rayluo]

This is a bugfix/enhancement release without any API change, and it will be automatically picked up by all downstream applications that accepts MSAL EX Python 0.3.x series.

• Enhancement: Better concurrency (Cache resiliency improvements #61, Cache resiliency #63, Skip read lock to improve concurrency #100)
• Bugfix: Now supports user home dir in drive root on Windows (Token cache persistence fails on Windows if home dir is drive root #83, Fixed failure when a user's home dir is a drive root on Windows #84)
• Enhancement: This package can now be run inside container
• Enhancement: Improvement compatibility with PyInstaller 3.5 on Python 2.7 (WindowsError: exception: access violation when using _MEMCPY #85, Specify memcpy argtypes #91)
• Enhancement: Catchable exception when persistence is unavailable (API for testing whether persistence is available #92, Raise without log polluting the console #93)
• Enhancement: Support dependency portalocker 2.0+ (Support portalocker >=2 #94, Allow portalocker 2 on Python 3.5+ #97)
• Enhancement: Improve documentation (PersistedTokenCache.deserialize doesn't persist data #77, Document the design goals and scopes #102)
• Including license in release package (Mention licence #76)

CC: @jiasli