Changing the @OutputFile on LessTask to a @OutputDirectory

Changing the defined output of the LessTask from Directory to
File. The variable is treated as a directory (i.e. sent in as
a first param in the two param File constructor) and using the
OutputFile annotation causes gradle to do some funky stuff and
error out with something like 'cannot write to output X because
it is a directory'.

This also enables gradle output directory auto creation.
Trivia, getting rid of compiler warnings

Received some compiler warnings from java files from the
groovy/java joint compiler. Turned on compiler flags to see
what the warnings were about and added a SuppressWarnings
annotation in one java source file.
Changing less task name to lesscss due to name conflict

The LessExtension is registered with the project with the name
'less'. This means that writing:

less {
  source = x
  dest   = y
}

is actually _not_ configuring the task but is instead just
setting some variables on the 'less' extension. This can be
proven by doing a 'println less.class.name' which prints out
x.y.z.LessExtension_Decorated and not x.y.z.LessTask_Decorated.

I have left the extension with the name 'less' and changed the
task name (and references in the plugin and test code) to
'lesscss'. This seems to work better, the plugin.gradle code
seems to do what it is supposed and my project using the task
can now successfully call the task with expected results.
Merge pull request #10 from mbjarland/master

Changing LessTask @OutputFile into a @OutputDirectory as it was breaking builds