Remove unused variables from :build_server
Group framework tasks in :build_server
Group frank tasks in :build_server
Group dylib tasks
Rename 'dir' to 'calabash-server-dir'
Framework 'constants' are not necessary

* FRAMEWORK and ZIP_FILE do not need to be constants.
* refactor: renamed the variables for clarity
'FRANK_LIB' does not need to be a constant

* Refactor: rename variables for clarity.
'DYLIB_PATHS' does not to be a constant

* Refactor: renamed variable for clarity
Expect the dylibs in 'calabash-dylibs' directory

calabash.dylib is confusing; there is no .dylib directory name
convention on MacOS.
Dir.chdir is clearer than FileUtils.cd

FileUtils.cd calls Dir.chdir, so let's call that method directly.
Keep 'dylibs' array local to dylib tasks
Update docs for :build_server task
No need for the 'build_server' function
Whitespace change: indent build_server task
Docs - deprecate build_server aliases

:install_server and :release_server are unused