New target description + moving target stuff under "framework"

Changing the way target descriptions work from a static mapping to
something that is dynamically generated and is extensible via plugins.
Also moving core target implementation stuff under "framework".

wa/framework/target/descriptor.py

@@ -24,35 +24,6 @@ def get_target_descriptions(loader=pluginloader):
     return targets.values()
 
 
-def instantiate_target(tdesc, params, connect=None):
-    target_params = {p.name: p for p in tdesc.target_params}
-    platform_params = {p.name: p for p in tdesc.platform_params}
-    conn_params = {p.name: p for p in tdesc.conn_params}
-
-    tp, pp, cp = {}, {}, {}
-
-    for name, value in params.iteritems():
-        if name in target_params:
-            tp[name] = value
-        elif name in platform_params:
-            pp[name] = value
-        elif name in conn_params:
-            cp[name] = value
-        else:
-            msg = 'Unexpected parameter for {}: {}'
-            raise ValueError(msg.format(tdesc.name, name))
-
-    tp['platform'] = (tdesc.platform or Platform)(**pp)
-    if cp:
-        tp['connection_settings'] = cp
-    if tdesc.connection:
-        tp['conn_cls'] = tdesc.connection
-    if connect is not None:
-        tp['connect'] = connect
-
-    return tdesc.target(**tp)
-
-
 class TargetDescription(object):
 
     def __init__(self, name, source, description=None, target=None, platform=None, 
@@ -115,18 +86,6 @@ COMMON_TARGET_PARAMS = [
               Please see ``devlab`` documentation for information on the available
               modules.
               '''),
-    Parameter('load_default_modules', kind=bool, default=True,
-              description='''
-              A number of modules (e.g. for working with the cpufreq subsystem) are
-              loaded by default when a Target is instantiated. Setting this to
-              ``True`` would suppress that, ensuring that only the base Target
-              interface is initialized.
-
-              You may want to set this if there is a problem with one or more default
-              modules on your platform (e.g. your device is unrooted and cpufreq is
-              not accessible to unprivileged users), or if Target initialization is
-              taking too long for your platform.
-              '''),
 ]
 
 COMMON_PLATFORM_PARAMS = [