Moving human_readable formatting function out of __init__.

There is a module, where this function is used - formatter_functions. It
is at the same time the only place where it is used. No need to clutter
__init__.py with it.

ebook_converter/__init__.py

@@ -210,18 +210,3 @@ def force_unicode(obj, enc=constants_old.preferred_encoding):
                     if isinstance(obj, bytes):
                         obj = obj.decode('utf-8')
     return obj
-
-
-def human_readable(size, sep=' '):
-    """ Convert a size in bytes into a human readable form """
-    divisor, suffix = 1, "B"
-    for i, candidate in enumerate(('B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB')):
-        if size < (1 << ((i + 1) * 10)):
-            divisor, suffix = (1 << (i * 10)), candidate
-            break
-    size = str(float(size)/divisor)
-    if size.find(".") > -1:
-        size = size[:size.find(".")+2]
-    if size.endswith('.0'):
-        size = size[:-2]
-    return size + sep + suffix