Updated Logback to version 1.0.13
Fixed method documentation
Added utility class which closes a Closable when necessary and converts
an IOException into a runtime exception if needed (belongs to issue #30)
Changes to close an output stream on a file which must be rename before
renaming it (belongs to issue #30)
Simplified code since utility class Closeables is available (belongs to
issue #30)
Replaced 'ConditionalCheck.notNull' with 'Check.notNull' and added test
case to cover this branch
Removed redundant check and added additional test case
Separated out test cases for 'deleteFile' and replaced redundant code to
delete a file
Removed unneeded catch-block
Removed unused import
Updated misleading method documentation
Simplified non-negative check by using 'Check.notNegative(long, String)'