calendar/time pattern

info recogida de: http://java.sun.com/j2se/1.4.2/docs/api/java/text/SimpleDateFormat.html

Letter	Date or Time Component	Presentation	Examples
G	Era designator	Text	AD
y	Year	Year	1996; 96
M	Month in year	Month	July; Jul; 07
w	Week in year	Number	27
W	Week in month	Number	2
D	Day in year	Number	189
d	Day in month	Number	10
F	Day of week in month	Number	2
E	Day in week	Text	Tuesday; Tue
a	Am/pm marker	Text	PM
H	Hour in day (0-23)	Number	0
k	Hour in day (1-24)	Number	24
K	Hour in am/pm (0-11)	Number	0
h	Hour in am/pm (1-12)	Number	12
m	Minute in hour	Number	30
s	Second in minute	Number	55
S	Millisecond	Number	978
z	Time zone	General time zone	Pacific Standard Time; PST; GMT-08:00
Z	Time zone	RFC 822 time zone	-0800

Crear un servicio para calculo de intervalo entre dos fechas

Conversores de datos: Calendar to String, y String to Calendar

A través de TDD generar un ServicioCalendarios que contenga funcionalidad relacionada con fechas y tratamiento de estas, incluyendo la comprobacion del intervalo entre dos fechas (necesario para funcionlidad de reserva en biblioteca)