doc: Fix bugs and update

Rebar is now on GitHub, so links did not work.
Some of the 'ls' lines where mixed up.
"How can I make my new gen_server do something?" was unclear where to
put what. Function say_hello was incomplete.
"How can I test?" was not formatted so unreadable.
Fixed more links.
doc: update part 2
Merge pull request #620 from ArthurClemens/doc_rebar

doc: Fix bugs and update
core: added 'magick' image filter options. Fixed mime lookup if lossless filter was inside a mediaclass definition.
core: fixed mediaclass lookup - now all lookups are done as documented with adherence to the module priority and the ua lookup.
doc: clarified validate param 'name'

Made it clear(er) the the user/programmer needs to add the name param in case name and id are unequal.
Merge pull request #624 from ArthurClemens/patch-4

doc: clarified validate param 'name'
doc: added example call for retrieving actual stats

Also aligned example code with described data structure: renamed 'example' to 'something'.
Merge pull request #625 from ArthurClemens/patch-5

doc: added example call for retrieving actual stats
mod_base: controller_static_pages: Expose all context arguments when rendering templates.
mod_admin_modules: Add menu for remote repository integration
mod_admin_modules: Add button link to open ZMR dialog form
mod_admin_modules: Add zmr dialog form template.

This template lists all the modules from the modules
repository server. It also comes with a text input for filtering the
modules listed in the table. Future work will be;

* Get zmr server from current Zotonic node. It is currently hard coded into the
 client code.
* Cache results on first try
* Test UI other browsers, especially mobile
* Install modules.
* Ability to refresh the data
* Make table scrollable, so items at the bottom can be accessed.
mod_admin_modules: Add borders to ZMR dialog table
mod_admin_modules: Move footer items to the top as menu
mod_admin_modules: Move js and css into lib directory
Untrack emacs buffers
mod_admin_modules: Add pointer cursor on mouse over
mod_admin_modules: Attach event to ZMR refresh button
mod_admin_modules: Cleanup code

Rename all functions, and html elements to confrom to Zotonic's naming convention.
Other changes include:

* Change table row background colour when clicked. This is to indicate that is has been selected
* When an already highlighted row is clicked, remove module from list of modules to install
* Dsiplay a helpful message while the module list are fetched from the server
* Do not display growl message after fetching the latest modules from the server
* The ZMM table is no longer striped, as it was interfering with the highlighting of tables
* Add "install" button when a row is clicked/selected. This is only done when the "install" button is not visible