Merge branch 'SES-1982' of bitbucket.org:openrdf/sesame into SES-1983
Merge branch 'SES-1957' of bitbucket.org:openrdf/sesame into SES-1983
Merge branch 'SES-1983' of bitbucket.org:openrdf/sesame into SES-1983
Created new branch SES-1986
Add support for SERIALIZABLE to SailBase
Merge branch 'SES-1986' of bitbucket.org:openrdf/sesame into SES-1986
Created new branch SES-1987
Merge branch 'SES-1986' of bitbucket.org:openrdf/sesame into SES-1987
Remove REPEATABLE_READ
Change incompatible isolation level from a warning to fatal error
Merge branch 'master' of bitbucket.org:openrdf/sesame into SES-1986
Merge branch 'master' of bitbucket.org:openrdf/sesame into SES-1987

Conflicts:
	core/model/src/main/java/org/openrdf/IsolationLevels.java
Rename isActiveOperation() to isQueuingWrites()
Fix IsolationLevelsTest logic
Merged in SES-1986 (pull request #232)

Support SERIALIZABLE isolation in MemoryStore and NativeStore
Merge branch 'master' of bitbucket.org:openrdf/sesame into SES-1987
Merged in SES-1987 (pull request #233)

Drop REPEATABLE_READ in favour of isolation levels that provide more consistency
Fix NPE in isQueuingWrites()
Flush changes on prepare/commit even if open operation
Restart queuing changes if commit called while open operation