Now try and finds Homebrew path using which, but still asks user for path if it fails.

Fills up options windows values if they are set.
Improved environment and brew path detection.
Added invalid shell warning.
Added more debug info.
Added message if user shell is not in the valid shells file.
Added warning if returned environment variables are malformed.
Fixed bug where not all output information would be printed.
Changed `weak` reference of `BPUpdateDoctorController` to `unsafe_unretained`.
Added explicit search feature. Renamed and refracted all typedef enums.
Fixed plural form of Formula on search box.
Removed perform like login shell argument.
Changed aboutWindowController to load lazy (lazy initialization).
Merge pull request #46 from xhruso00/reduce-memory-footprint

Little memory footprint reduction
Improved environment variables detection algorithm.

Also removed the constraint added in issue #33 because it caused the sidebar cells to move on the screen when selected (Maybe is a bug in Xcode).
Bumped build.
Prints environment query result.
Refracted brew tasks to run from inside bash commands, thus implicitly importing the user’s default shell and its environment variables.

Removed annoying “Test” tooltip from main window.
Removed custom brew path window and disabled preferences window.

These both are no longer necessary. The current implementation runs Homebrew from an instance of the user’s default shell, thus implicitly importing all user’s default environment variables.
Therefore, if a command works on Homebrew, it should work on Cakebrew.
Changed debug warning string.