SES-1901 draft setup for configurable transaction isolation levels.
Merge branch 'master' into ses-1901
SES-1901 added additional isolation levels as discussed on developers
mailinglist.
SES-1901 added getter/setter in RepositoryConnection for the isolation
level.
SES-1901 javadoc version mentions updated.
Merge branch 'master' into ses-1901
SES-1901 added isCompatibleWith to IsolationLevel, added functionality
for registering supported isolation leves of a particular Sail, added
implementation for selecting "closest compatible" isolation level when
setting a level.
Merge branch 'master' of bitbucket.org:openrdf/sesame into ses-1901

Conflicts:
	core/sail/federation/src/main/java/org/openrdf/sail/federation/AbstractFederationConnection.java
	core/sail/federation/src/main/java/org/openrdf/sail/federation/Federation.java
cleanup
further cleanup
SES-1901 re-added exception to getDelegate() method declaration.
SES-1901 introduced IsolationLevel interface, enum implements, all
public methods now use the interface to allow third-party custom levels.
SES-1901 : Add @Override annotations to RepositoryConnectionWrapper

This would have made the incorrect begin(IsolationLevels) overriden
method a compile error if it was used consistently before.
SES-1901 : Use IsolationLevel in Sail.getSupportedIsolationLevels
SES-1901 : Add getDefaultIsolationLevel to Sail 

This enables users to be aware of what will be used by
SailConnection.begin()
SES-1901 : Add begin(IsolationLevel) to SailRepositoryConnection
SES-1901 : Add @Override to methods in SailConnectionBase
SES-1901 : Add @Override to SailConnectionWrapper

Include note about case where size(Resource) is redundant, but keeping
for binary compatibility, as Java links to size(Resource) distinctly
from size(Resource...) until the bytecode is recompiled.
SES-1901 : Add @Override to SailWrapper
SES-1901 : Add @Override to more classes