Fixes race that can cause duplicate writes in XaLogicalLog

There is a possible window where a transaction may fail to flush
 the log buffer (for example, during a commit) and even though
 it will set the KernelHealth to notOk, another thread can still
 come and try to flush the same contents again (say, by attempting
 a commit of its own tx). This can cause the log to be unrecoverable.
 This commit fixes this issue by introducing checks to KernelHealth
 before any write happens to the log's underlying file.
Merge pull request #2326 from digitalstain/1.9-fix-damaged-log-writes

Fixes race that can cause duplicate writes in XaLogicalLog
added script to detect unauthorized contributors
added script to detect unauthorized contributors
fix for TopPipe with duplicate values
Make sure old icons aren't used in the manual.
Merge pull request #2332 from jexp/top-n-fix

fix for TopPipe with duplicate values
Merge pull request #2335 from nawroth/2.0-maint

Make sure old icons aren't used in the manual
Merge branch '1.9-maint' into 1.9-merge

Conflicts:
	community/kernel/src/main/java/org/neo4j/kernel/impl/transaction/xaframework/XaLogicalLog.java
	community/kernel/src/test/java/org/neo4j/kernel/impl/transaction/xaframework/XaLogicalLogTest.java
2.0.3 changelogs
Merge pull request #2339 from jakewins/1.9-merge

1.9 merge
Added +UNWIND+ to Cypher

UNWIND can be used to transform a collection into individual rows.
Minor changes to UNWIND

o Added more a few more tests for edge cases
o UNWIND now does not remove anything from scope,
  only adds a new identifier for the elements
o Tweaked the documentation
Add UNWIND to shell
Add UNWIND to the browser