Rewrite ProcessResources collector

Features:
  * new metrics
  * performance improvements:
    - get full info only from processes that matched
    - get all info at once
    - do not reinitialize configuration on collection
  * no support for blocking cpu_percent (causes gaps in graphs)
  * change the default path to /process

Known bugs:
  * tests do not work
  * no support for units because we have a lot of different metrics now

BTW, should fix this:
```
[2014-01-15 21:27:12,568] [Thread-1] Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.7/diamond/collector.py", line 393, in _run
    self.collect()
  File "/usr/share/diamond/collectors/processresources/processresources.py", line 175, in collect
    self.filter_processes()
  File "/usr/share/diamond/collectors/processresources/processresources.py", line 165, in filter_processes
    if process_filter(proc, cfg):
  File "/usr/share/diamond/collectors/processresources/processresources.py", line 70, in process_filter
    if name.search(proc.name):
  File "/usr/lib/python2.7/dist-packages/psutil/_common.py", line 85, in __get__
    ret = self.func(instance)
  File "/usr/lib/python2.7/dist-packages/psutil/__init__.py", line 345, in name
    name = self._platform_impl.get_process_name()
  File "/usr/lib/python2.7/dist-packages/psutil/_pslinux.py", line 470, in wrapper
    raise NoSuchProcess(self.pid, self._process_name)
NoSuchProcess: process no longer exists (pid=2781)
```