Change gopivotal.com to pivotal.io

This commit changes email addresses and URLs so that they point to
pivotal.io instead of gopivotal.com.
JavaMailSenderImpl catches Exception instead of MessagingException and checks for reconnect in case of message batches

Issue: SPR-12298
Further locking optimizations for the retrieval of non-singleton beans

Issue: SPR-12250
Provider declaration for @Value method argument works again

Issue: SPR-12297
JsonPath dependency upgraded to 1.1

Issue: SPR-12299
Consistent reset of resource holders on doBegin failure

Issue: SPR-12280
Comprehensive revision of SpEL's bytecode generation and number handling (BigInteger support, doubleValue fallback)

Issue: SPR-9913
Polishing
Fix reference code sample
Fix outdated references to JobDetailBean

Issue: SPR-12306
TextMessage.toString() does not throw StringIndexOutOfBoundsException for payload with multibyte characters

Issue: SPR-12307
WebSocketSession extends java.io.Closeable, plus reorganization of AbstractSockJsSession's code

Issue: SPR-12311
Explicitly detect (and prevent) private @Scheduled methods on CGLIB proxies

Issue: SPR-12308
Consistent use of LinkedHashSet for interfaces (since interface order may matter in subtle cases)
Add shortcuts for Jackson mix-in annotations registration

This commit adds support for direct Jackson mix-in annotations registration in
Jackson2ObjectMapperFactoryBean and Jackson2ObjectMapperBuilder.

Issue: SPR-12144