Can't compile with java 8

./bin/build returns the following lines when my java version is set to oracle-java8 on ubuntu,

```
$ ./bin/build.sh
unzipping JARs...
making cached JAR....
compiling...
compiling with 'scalac'...
compiling common...
warning: [options] bootstrap class path not set in conjunction with -source 1.5
warning: [options] source value 1.5 is obsolete and will be removed in a future release
warning: [options] target value 1.5 is obsolete and will be removed in a future release
warning: [options] To suppress warnings about obsolete options, use -Xlint:-options.
Note: net.appjet.common/util/HttpServletRequestFactory.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: net.appjet.common/util/HttpServletRequestFactory.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
4 warnings
error: error while loading AnnotatedElement, class file '/usr/lib/jvm/java-8-oracle/jre/lib/rt.jar(java/lang/reflect/AnnotatedElement. class)' is broken
(bad constant pool tag 18 at byte 76)
error: error while loading CharSequence, class file '/usr/lib/jvm/java-8-oracle/jre/lib/rt.jar(java/lang/CharSequence.class)' is broke n
(bad constant pool tag 18 at byte 10)
two errors found
cp: cannot stat ‘/opt/hackpad/infrastructure/build/appjet.jar’: No such file or directory
```