fix omit fixed effects label bug

[jrstromme]

The following code produces a bug with the omit labels:

x <- rnorm(100)
z <- rnorm(100)
a <- rnorm(100)

fit1.lm <- lm(y~a+x)
fit2.lm <- lm(y~a+x+z)
# doesnt work, z should be 'yes' column 2
stargazer(fit1.lm, fit2.lm,
              omit=c("x", "z"), 
              omit.labels=c("x", "z")) 

This bug is due to a 'cbind' command dropping items if you try to cbind(matrix,vector) when length(vector) is larger than nrow(matrix).

I am not 100% sure, but I think that this 'dropping' issue is not by design in the code and will fix this bug without causing other issues.