Some more logo style parameters

[mohierf]

Allow more configuration for the application logo in header bar and login form.

As of settings.cfg:

; # Login form
; ------------------------------------------------------------------------------------------
; Welcome text in the login form.
; Default is:
; Welcome<br> Log-in to use the application
; login_text=Welcome to Alignak WebUI<br> Log-in to use the application
login_text=Welcome to <strong>Alignak WebUI</strong><br> Log-in to use the application

; Application logo in the login form
; Default logo is: /static/images/alignak_white_logo.png
; Uncomment this line if you wish to use a blue version of the alignak logo, else specify your url
;app_logo=/static/images/alignak_blue_logo.png

; # Navigation bar & login form
; ------------------------------------------------------------------------------------------
; The default defined Css for the logo image is:
; .navbar-brand img {
;    height: 100%;
;    padding: 3px;
;    background-color: rgba(255,255,255,0.8);
;    border-radius: 5px;
; }
; You can change this default Css in the configuration variables: app_logo_css and login_logo_css

; The content of this variable will be specified as the style of the img element in the header bar
; app_logo_css=background-color: rgba(255,255,255,0.8); border-radius: 5px;
; Uncomment this line to use the alignak blue logo, else specify your Css for the header bar logo

; The content of this variable will be specified as the style of the img element in the login form
; Note that, as default, the login form image style is width:90%
; login_logo_css=margin:1%%;padding:1%%;
; login_logo_css=

; Default logo title
; app_logo_title=Alignak Web User interface

[coveralls]

Coverage remained the same at 82.15% when pulling 341a3b23f36159dbaae64bc5ed661d946407bebc on logo-style into bc59b6be69bd26a76ba17faeeefa59cd61266a6e on develop.