Implementation of S3 method for survfit class

[survfit class](http://stat.ethz.ch/R-manual/R-devel/library/survival/html/survfit.html)
**Basic examples**
```
require(survival)
hmohiv<-read.table("http://www.ats.ucla.edu/stat/r/examples/asa/hmohiv.csv", sep=",", header = TRUE) 
mini<-hmohiv[ID<=5,]
attach(hmohiv)
mini.surv <- survfit(Surv(time, censor)~ 1, conf.type="none")
pander(mini.surv)
attach(hmohiv)
h.surv <- survfit(Surv(time, censor)~ 1, conf.type="log-log")
pander(h.surv)
```