Fixed bug in 'oe' script when passing no arguments

When no arguments passed to 'oe' script next exception was thrown:

```
Traceback (most recent call last):
  File "./oe", line 5, in <module>
    if sys.argv[1] == 'run-tests':
IndexError: list index out of range
```

[FIX] indentation and formatting of various rst snippets

Added openerp-gevent and oe to 'scripts' section in setup.py

[FIX] report set_html_image error

Dereferencing of nones could lose error messages during import

[FIX] missing gitignore server rules

previous port only had the web client's rules

First howto: tutorial to basic website features (dev-wise)

Server-side, view extension is done via xpath. This includes "template" views
full of HTML.

HTML elements often have a bunch of classes, sometimes even semantic
(!). XPath is generally great, but specifically lousy at dealing with
space-separated values: in standard XPath 1.0 to know if an element has a
class 'foo' the predicate is:

    contains(concat(' ', normalize-space(@class), ' '), ' foo ')

and this has to be fully duplicated if there's a second class involved.

Things are slightly better with EXSLT/XPath 2.0 and tokenize, but still not
great:

    tokenize(@class, '\s+') = 'foo'

and the equality check is very weird when unaware of XPath's evaluation rules.

``hasclass`` makes this much simpler to deal with: to get any ``foo`` node
with the class ``bar`` is as simple as:

    //foo[hasclass('bar')

and it can take multiple class, as with e.g. jquery it will return elements
with all specified classes.

Beware though, the predicate function will be called once for each element to
check, since it's implemented in pure python and not profiled elements should
be filtered as much as possible before this point.

auth=public is not necessary to depending on website, however rendering within website/website's layout blows up if there is no current user