added installed module (helper)

ess/__init__.py

 import TraceWin
+import installed

ess/installed.py

+def get_installed_packages():
+    '''
+    Returns a dictionary of installed packages
+
+    Example usage:
+    (print all packages):
+    for package in get_installed_packages():
+        print package
+    '''
+    import pip
+    installed_packages = pip.get_installed_distributions()
+    installed_packages_list = sorted(["%s==%s" % (i.key, i.version)
+         for i in installed_packages])
+    return installed_packages
+
+def is_package_installed(name):
+    '''
+    Returns a bool, true if package name
+    was found in one of the string representations
+    of any package.
+
+    case insensitive (meaning Package==package)
+    '''
+    name=name.lower()
+    ret=False
+    for package in get_installed_packages():
+        if name in str(package).lower():
+            print "Found",package
+            ret=True
+    return ret