Help text should be consistently capitalised

[Sunil Shah]

The first lines are not consistently capitalised.

For example:

usage: mesos-find [-h] [-v] [-q] task [path]

List all the files inside a specific task's sandbox

positional arguments:
  task           Name of the task. Note that this can be a partial match.
  path           Path to view. (default: )

optional arguments:
  -h, --help     show this help message and exit
  -v, --version  show program's version number and exit
  -q             Suppresses printing of headers when multiple tasks are being
                 examined (default: False)

Versus:

usage: mesos-head [-h] [-v] [-n N] [-q] task [file [file ...]]

display first lines of a file

positional arguments:
  task           ID of the task. May match multiple tasks (or all)
  file           Path to the file inside the task's sandbox. (default:
                 ['stdout'])

optional arguments:
  -h, --help     show this help message and exit
  -v, --version  show program's version number and exit
  -n N           Number of lines of the file to output. (default: 10)
  -q             Suppresses printing of headers when multiple tasks are being
                 examined (default: False)