[#1880] Fix file handle leak in VirtualFile.content and VirtualFile.contentAsString
[#1880] Close resources in finally block to avoid file handle leaks in case of exceptions
[#1880] Use commons-io API to fix wrong usage of InputStream.read()
[#1880] Use commons-io API to avoid re-inventing the wheel
[#1880] Use commons-io API to avoid re-inventing the wheel -  fixed compilation error
[#1880] Use commons-io API to avoid re-inventing the wheel -  fixed compilation error with Java 6
Merge pull request #806 from codeborne/close-streams

[#1880] Fix file handle leaks