Wait for file creation before continue for appendSDF test

Hack to make the test pass.
Resource check when testing file operation should be built in to our test framework.
Also adds more information when testBug3394 fails
Make use of SilenChemObjectBuilder 

instead of DefaultChemObjectBuilder
Unregister listener when disposed

Should solve bug 3547
Makes chemspider require version 1.1.1 of org.apache.commons.logging

to force it to use the slf4j version
Adds ability to be adapted to ImageDescriptor
Replace equals and adds hash code

The molecules should be equal if they have the same CID
Both methods are generated by eclipse