US001: Start new activity

[ototo]

User Story 001: Start new activity

As a user of yourTime application I want to be able to record the moment when I start new activity together with that activity's summary.

Expected CLI interface:

$ yt start All the other parameters go to activity summary.
+ [1] 09:00 All the other parameters go to activity summary.

Running activities:
00:00 (09:00>) All the other parameters go to activity summary.

Notes:

1. After staring new activity, the application prints out the id and timestamp for the moment when it was started followed by its summary string.
2. Afterwards it prints a list of currently ongoing activities with duration, start timestamp and summary string.
3. Ids for new activities are generated by incrementing the last used id (1-based) with one.

[ototo]

Tasks:

1. Create command handler for start command.
2. Create command parsier.
3. Create database infrastructure.