OTWO-4588 Return empty svn tags if it is non-tagged repository

[Priya5]

No description provided.

[rapbhan]

LGTM

[PDegenPortnoy]

Why was this the correction? What was the root cause that this addresses?

[Priya5]

For svn repository which does not have tags,

ohloh_scm/lib/ohloh_scm/adapters/svn/misc.rb

Line 147 in 9acff30

tag_strings = `svn ls -v #{ base_path}/tags`.split(/\n/)

will return empty array.
Running [ ][1..-1] on it will return nil, which causes the issue. So, I have used [ ].drop(1), which will return [ ].

[PDegenPortnoy]

For posterity, the end[1..-1] code returns the rest of the array by skipping the first element. However, for an empty array, this returns nil, which causes problems downstream. The method needs to return an array. Changing that line to end.drop(1) will return the rest of the array by dropping the first element, but will always return an array even if the array was empty to start iwth.