Simple command-line interface

As a geek investor, I want to see my stock quotes through the terminal:
```sh
$ bovespa

  Usage:
    bovespa PETR4
    bovespa petr4          # lower case is ok
    bovespa PETR4 VALE5    # multiple stock codes
```

Sample:
```sh
$ bovespa PETR4
PETR4 - Open: 16.0  Last: 16.05  Min: 15.91  Max: 16.29  Avg: 16.17  Var: 0.24
```

The interface makes it easy to show a full stock portfolio with the help of an alias:
```sh
# .bash_profile
alias my_stocks="bovespa PETR4 VALE5 BBAS3 PSSA3 PDGR3"
```

Sample:
```sh
$ my_stocks
PETR4 - Open: 16.0  Last: 16.05  Min: 15.91  Max: 16.29  Avg: 16.17  Var: 0.24
VALE5 - Open: 28.11  Last: 28.1  Min: 27.95  Max: 28.43  Avg: 28.18  Var: 0.21
BBAS3 - Open: 22.3  Last: 22.49  Min: 22.23  Max: 22.87  Avg: 22.55  Var: 0.84
PSSA3 - Open: 25.9  Last: 25.75  Min: 25.69  Max: 26.17  Avg: 25.85  Var: -0.57
PDGR3 - Open: 1.81  Last: 1.92  Min: 1.8  Max: 1.95  Avg: 1.91  Var: 4.32
```