Build options for build.sh, clean.sh and rebuild.sh changed

Options
-------

Option -d          build in debug mode
Option -r          build in release mode
Option -a          build both in debug and release modes
Option -l <path>   use specified path as path to libs folder

If lib path (-l) wasn't specified, <robomongo>/libs folder will be used.
If no args were specified, it will be debug build.

Example
--------

./build.sh -r
./build.sh -d -l /path/to/libs
Merge branch 'master' of https://github.com/paralect/robomongo