#4 Apache HttpClient 4.1, MS SQL Server JDBC driver, database shutdown handling

[Mark Pollard]

A variety of enhancements, including:

1. Changes to support the following environment: Hibernate 4.2.6 (with schema validation enabled [database metadata]), Microsoft SQL Server, Microsoft SQL Server JDBC driver (sqljdbc4.jar)
   a. ConnectionPrepareStatementCommand: ObjectOutput.writeUTF() is limited to 65,535 bytes, so output raw bytes
   b. RowPacket: SQL Server JDBC driver small int handling
   c. StreamingResultSet: SQL Server JDBC driver clob and timestamp handling
2. Convert VJDBC to use Apache HttpClient 4.1
3. Use KeepAliveTimerTask across all connections
4. Generally named all threads and set to daemon
5. Closed ResultSet in TableCache
6. Eliminated several finalize() statements
7. Converted isValid() from sleep-based approach to wait
8. Improved handling of unexpected database shutdown (see usage of ConnectionClosedException, UnknownConnectionException)
9. Similar to RequestEnhancer pattern, introduced ResponseHandler to allow inspection of response headers
10. Allow HTTP SSL hostname and certificate verification to be disabled
11. Support public key pinning for HTTP SSL host verification (see https://www.owasp.org/index.php/Certificate_and_Public_Key_Pinning)
12. Ensure only a single DBCP connection pool is instantiated