initial commit for slave placement

still need tests
some slave placement tests
name change
name tweak
Proxy history manager calls
Use noop HistoryManager when no database avail
Remove singleton annotation

It currently doesn’t work with SingularityStartable.
remove nonNull
Remove verbose test logs.
Merge pull request #235 from HubSpot/optional_mysql

Make (My)SQL optional
Merge branch 'master' into slave_placement

Conflicts:
	SingularityService/src/main/java/com/hubspot/singularity/config/SingularityConfiguration.java
use a singleton in test.
enhanced readme
Merge pull request #232 from HubSpot/slave_placement

support for slave placement
more cleanup
improvements to cool down email
use com.sun.mail
Further cool down email cleanup
dont need custom build
Merge branch 'master' into fix-vagrant