[WIP] Refactor Mac installation

Using "displayAndExec" and "displayTitle" functions.
Fixing some bugs
[WIP] Working on installation improvements (OS X)
Refactoring bash functions
English spelling corrections
Some others spelling fixes
New log bash functions

Now, CentralReport installer can write messages in the log files (/var/log/centralreport.log). Log functions have some log levels (info, error, etc…)
[WIP] First wave of fixes
Updated : log function names
Some minor fixes
Spelling fixes
Merge pull request #16 from miniche/feature-install-mac

Refactor installation scripts