[FIX] ir_qweb: css asset: use which to find lessc and sass

Also, use lessc.cmd instead of lessc on Windows. It allows to run
lessc command with only nodejs and the less module (no cygwin).

openerp/addons/base/ir/ir_qweb.py

@@ -28,7 +28,7 @@ import openerp.tools.lru
 from openerp.http import request
 from openerp.tools.safe_eval import safe_eval as eval
 from openerp.osv import osv, orm, fields
-from openerp.tools import html_escape as escape
+from openerp.tools import html_escape as escape, which
 from openerp.tools.translate import _
 
 _logger = logging.getLogger(__name__)
@@ -1529,14 +1529,21 @@ class SassStylesheetAsset(PreprocessedCSS):
         return "/*! %s */\n%s" % (self.id, content)
 
     def get_command(self):
-        return ['sass', '--stdin', '-t', 'compressed', '--unix-newlines', '--compass',
-               '-r', 'bootstrap-sass']
+        defpath = os.environ.get('PATH', os.defpath).split(os.pathsep)
+        sass = which('sass', path=os.pathsep.join(defpath))
+        return [sass, '--stdin', '-t', 'compressed', '--unix-newlines', '--compass',
+                '-r', 'bootstrap-sass']
 
 class LessStylesheetAsset(PreprocessedCSS):
     def get_command(self):
+        defpath = os.environ.get('PATH', os.defpath).split(os.pathsep)
+        if os.name == 'nt':
+            lessc = which('lessc.cmd', path=os.pathsep.join(defpath))
+        else:
+            lessc = which('lessc', path=os.pathsep.join(defpath))
         webpath = openerp.http.addons_manifest['web']['addons_path']
         lesspath = os.path.join(webpath, 'web', 'static', 'lib', 'bootstrap', 'less')
-        return ['lessc', '-', '--clean-css', '--no-js', '--no-color', '--include-path=%s' % lesspath]
+        return [lessc, '-', '--clean-css', '--no-js', '--no-color', '--include-path=%s' % lesspath]
 
 def rjsmin(script):
     """ Minify js with a clever regex.