Adds a support of SOAP API for Apex

See http://www.salesforce.com/us/developer/docs/apexcode/index_Left.htm#StartTopic=Content/apex_api.htm for details of SOAP API for Apex.

The new classes in 'com.sforce.soap.apex' package are generated by the following steps.

1)login Salesforce
2)go to [Setup | App Setup | Develop | API]
3)download Apex WSDL
4)install and build Force.com WSC (see https://github.com/forcedotcom/wsc)
5)create "target/force-apex-src" directory under the WSC directory
  $ cd wsc
  $ mkdir target/force-apex-src
6)generate stubs from Apex WSDL you download at the step 3 above
  $ java -classpath target/force-wsc-28.0.0-jar-with-dependencies.jar com.sforce.ws.tools.wsdlc apex.wsdl target/force-apex-28.0.0.jar target/force-apex-src

This commit includes '.java' files generated in 'target/force-apex-src/com/sforce/soap/apex' directory.